From a17f6dff0ba4eb2a8716c37a74d5b103892a7eee Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Mon, 28 Oct 2024 20:22:26 +0530
Subject: [PATCH 01/26] add: init project files

---
 .gitignore | 3 +++
 go.mod     | 3 +++
 main.go    | 5 +++++
 3 files changed, 11 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 go.mod
 create mode 100644 main.go

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 000000000..874cb3137
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+.idea
+main
+
diff --git a/go.mod b/go.mod
new file mode 100644
index 000000000..ee6c779c5
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/sreeram77/challenge2016
+
+go 1.23.1
diff --git a/main.go b/main.go
new file mode 100644
index 000000000..790580777
--- /dev/null
+++ b/main.go
@@ -0,0 +1,5 @@
+package main
+
+func main() {
+
+}

From 30ef7cd30c26ad66a2cfecd76375511524f36ba3 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Mon, 28 Oct 2024 20:35:57 +0530
Subject: [PATCH 02/26] add: Region and Distributor models

---
 models/distributor.go | 23 +++++++++++++++++++++++
 models/region.go      | 22 ++++++++++++++++++++++
 2 files changed, 45 insertions(+)
 create mode 100644 models/distributor.go
 create mode 100644 models/region.go

diff --git a/models/distributor.go b/models/distributor.go
new file mode 100644
index 000000000..46034e4d0
--- /dev/null
+++ b/models/distributor.go
@@ -0,0 +1,23 @@
+package models
+
+type Distributor struct {
+	Name            string
+	IncludeRegions  []Region
+	ExcludedRegions []Region
+}
+
+func (d Distributor) String() string {
+	res := "Name: " + d.Name + "\n"
+
+	res += "INCLUDE:"
+	for _, region := range d.IncludeRegions {
+		res += region.String() + "\n"
+	}
+
+	res += "EXCLUDE: "
+	for _, region := range d.ExcludedRegions {
+		res += region.String() + "\n"
+	}
+
+	return res
+}
diff --git a/models/region.go b/models/region.go
new file mode 100644
index 000000000..11602a7bc
--- /dev/null
+++ b/models/region.go
@@ -0,0 +1,22 @@
+package models
+
+type Region struct {
+	CountryCode  string `csv:"Country Code"`
+	ProvinceCode string `csv:"Province Code"`
+	CityCode     string `csv:"City Code"`
+}
+
+func (r Region) String() string {
+	res := ""
+
+	for i, v := range []string{r.CountryCode, r.ProvinceCode, r.CityCode} {
+		if v != "" {
+			if i != 0 {
+				res += "-"
+			}
+			res += v
+		}
+	}
+
+	return res
+}

From 0130b08ab24919d73b5d24dddcc7406b303f88fe Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Mon, 28 Oct 2024 20:48:20 +0530
Subject: [PATCH 03/26] add: countries model to store geography

---
 go.mod              |  2 +-
 models/geography.go | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 models/geography.go

diff --git a/go.mod b/go.mod
index ee6c779c5..8e4ec9e65 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,3 @@
-module github.com/sreeram77/challenge2016
+module challenge2016
 
 go 1.23.1
diff --git a/models/geography.go b/models/geography.go
new file mode 100644
index 000000000..b01a6167f
--- /dev/null
+++ b/models/geography.go
@@ -0,0 +1,19 @@
+package models
+
+type Countries map[string]Country
+
+type Country struct {
+	Name      string
+	Code      string
+	Provinces Provinces
+}
+
+type Provinces map[string]Province
+
+type Province struct {
+	Name   string
+	Code   string
+	Cities Cities
+}
+
+type Cities map[string]string

From d6fc519f103a67708745f5b213a7c08544e61507 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Mon, 28 Oct 2024 21:22:40 +0530
Subject: [PATCH 04/26] add: csv package to parse file

---
 csv/load.go | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 csv/load.go

diff --git a/csv/load.go b/csv/load.go
new file mode 100644
index 000000000..1045bd208
--- /dev/null
+++ b/csv/load.go
@@ -0,0 +1,88 @@
+package csv
+
+import (
+	"encoding/csv"
+	"errors"
+	"os"
+
+	"challenge2016/models"
+)
+
+// Load reads a CSV file and returns a map of countries.
+func Load(file string) (models.Countries, error) {
+	// Load content from file.
+	content, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+
+	// Parse content as CSV.
+	reader := csv.NewReader(content)
+	if reader == nil {
+		return nil, errors.New("could not read CSV")
+	}
+
+	records, err := reader.ReadAll()
+	if err != nil {
+		return nil, err
+	}
+
+	countries := make(models.Countries)
+
+	for i, record := range records {
+		// Skip the first row
+		if i == 0 {
+			continue
+		}
+
+		country, exists := countries[record[2]]
+		if !exists {
+			cities := make(models.Cities)
+			cities[record[0]] = record[3]
+
+			province := models.Province{
+				Name:   record[4],
+				Code:   record[1],
+				Cities: cities,
+			}
+
+			provinces := make(models.Provinces)
+			provinces[record[1]] = province
+
+			country = models.Country{
+				Name:      record[5],
+				Code:      record[2],
+				Provinces: provinces,
+			}
+
+			countries[record[2]] = country
+
+			continue
+		}
+
+		province, exists := country.Provinces[record[1]]
+		if !exists {
+			cities := make(models.Cities)
+			cities[record[0]] = record[3]
+
+			province := models.Province{
+				Name:   record[4],
+				Code:   record[1],
+				Cities: cities,
+			}
+
+			country.Provinces[record[1]] = province
+
+			continue
+		}
+
+		_, exists = province.Cities[record[0]]
+		if !exists {
+			province.Cities[record[0]] = record[3]
+		}
+
+		province.Cities[record[0]] = record[3]
+	}
+
+	return countries, nil
+}

From 08ac768eeb7f24fee3c733c87f4ebd090883f4f6 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Mon, 28 Oct 2024 21:32:06 +0530
Subject: [PATCH 05/26] add: Distributors store interface

---
 store/store.go | 9 +++++++++
 1 file changed, 9 insertions(+)
 create mode 100644 store/store.go

diff --git a/store/store.go b/store/store.go
new file mode 100644
index 000000000..bc77fe9f5
--- /dev/null
+++ b/store/store.go
@@ -0,0 +1,9 @@
+package store
+
+import "challenge2016/models"
+
+type Distributors interface {
+	Insert(models.Distributor) error
+	Exists(name string) (bool, error)
+	CheckPermission(distributor string, region models.Region) (bool, error)
+}

From 9baf2b7d4eabc67b271b39f444033431612080b3 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Mon, 28 Oct 2024 21:33:26 +0530
Subject: [PATCH 06/26] update: add Parent in models.Distributor

---
 models/distributor.go | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/models/distributor.go b/models/distributor.go
index 46034e4d0..c5794def8 100644
--- a/models/distributor.go
+++ b/models/distributor.go
@@ -4,8 +4,20 @@ type Distributor struct {
 	Name            string
 	IncludeRegions  []Region
 	ExcludedRegions []Region
+	Parent          *Distributor
 }
 
+// NewDistributor returns a new distributor.
+func NewDistributor(name string, includeRegions []Region, excludedRegions []Region, parent *Distributor) *Distributor {
+	return &Distributor{
+		Name:            name,
+		IncludeRegions:  includeRegions,
+		ExcludedRegions: excludedRegions,
+		Parent:          parent,
+	}
+}
+
+// String returns a string representation of the distributor.
 func (d Distributor) String() string {
 	res := "Name: " + d.Name + "\n"
 

From 3e68fb38822b128a8eb0406f7d3882c37323dc43 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 13:50:19 +0530
Subject: [PATCH 07/26] add: Parse to parse Region from string

---
 models/region.go | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/models/region.go b/models/region.go
index 11602a7bc..ba6929fa8 100644
--- a/models/region.go
+++ b/models/region.go
@@ -1,5 +1,7 @@
 package models
 
+import "strings"
+
 type Region struct {
 	CountryCode  string `csv:"Country Code"`
 	ProvinceCode string `csv:"Province Code"`
@@ -20,3 +22,22 @@ func (r Region) String() string {
 
 	return res
 }
+
+func Parse(region string) Region {
+	split := strings.Split(region, "-")
+
+	var r Region
+
+	switch len(split) {
+	case 1:
+		r.CountryCode = split[0]
+		fallthrough
+	case 2:
+		r.ProvinceCode = split[1]
+		fallthrough
+	case 3:
+		r.CityCode = split[2]
+	}
+
+	return r
+}

From 5c00377d367539974bfd932c4402048b3bd2d6df Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 14:36:46 +0530
Subject: [PATCH 08/26] update: add ValidateRegion in Distributor

---
 models/distributor.go | 52 ++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 49 insertions(+), 3 deletions(-)

diff --git a/models/distributor.go b/models/distributor.go
index c5794def8..3f6576cee 100644
--- a/models/distributor.go
+++ b/models/distributor.go
@@ -8,12 +8,11 @@ type Distributor struct {
 }
 
 // NewDistributor returns a new distributor.
-func NewDistributor(name string, includeRegions []Region, excludedRegions []Region, parent *Distributor) *Distributor {
-	return &Distributor{
+func NewDistributor(name string, includeRegions []Region, excludedRegions []Region) Distributor {
+	return Distributor{
 		Name:            name,
 		IncludeRegions:  includeRegions,
 		ExcludedRegions: excludedRegions,
-		Parent:          parent,
 	}
 }
 
@@ -33,3 +32,50 @@ func (d Distributor) String() string {
 
 	return res
 }
+
+// ValidateRegion returns true if the region is authorized for the distributor.
+func (d Distributor) ValidateRegion(region Region) bool {
+	result := validateRegion(region, d.ExcludedRegions)
+	if result {
+		return false
+	}
+
+	result = validateRegion(region, d.IncludeRegions)
+	if result {
+		return true
+	}
+
+	return false
+}
+
+func validateRegion(region Region, regions []Region) bool {
+	for _, r := range regions {
+		// Exact match.
+		if r == region {
+			return true
+		}
+
+		if r.CountryCode != region.CountryCode {
+			continue
+		}
+
+		if r.ProvinceCode == "" {
+			return true
+		}
+
+		if r.ProvinceCode != region.ProvinceCode {
+			continue
+		}
+
+		if r.CityCode == "" {
+			return true
+		}
+
+		if r.CityCode != region.CityCode {
+			continue
+		}
+
+		return true
+	}
+	return false
+}

From cf7292c9f90383614b1ee79972270a7d48ad68bc Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 14:37:32 +0530
Subject: [PATCH 09/26] fix: Region parse failing to parse only CountryCode

---
 models/region.go | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/models/region.go b/models/region.go
index ba6929fa8..bc04c791c 100644
--- a/models/region.go
+++ b/models/region.go
@@ -31,11 +31,12 @@ func Parse(region string) Region {
 	switch len(split) {
 	case 1:
 		r.CountryCode = split[0]
-		fallthrough
 	case 2:
+		r.CountryCode = split[0]
 		r.ProvinceCode = split[1]
-		fallthrough
 	case 3:
+		r.CountryCode = split[0]
+		r.ProvinceCode = split[1]
 		r.CityCode = split[2]
 	}
 

From 22585676689469855741a8a6ed1208438b047685 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 14:37:53 +0530
Subject: [PATCH 10/26] refactor: countries to geography

---
 csv/load.go         | 4 ++--
 models/geography.go | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/csv/load.go b/csv/load.go
index 1045bd208..b3d6723d6 100644
--- a/csv/load.go
+++ b/csv/load.go
@@ -9,7 +9,7 @@ import (
 )
 
 // Load reads a CSV file and returns a map of countries.
-func Load(file string) (models.Countries, error) {
+func Load(file string) (models.Geography, error) {
 	// Load content from file.
 	content, err := os.Open(file)
 	if err != nil {
@@ -27,7 +27,7 @@ func Load(file string) (models.Countries, error) {
 		return nil, err
 	}
 
-	countries := make(models.Countries)
+	countries := make(models.Geography)
 
 	for i, record := range records {
 		// Skip the first row
diff --git a/models/geography.go b/models/geography.go
index b01a6167f..49f0c2288 100644
--- a/models/geography.go
+++ b/models/geography.go
@@ -1,6 +1,6 @@
 package models
 
-type Countries map[string]Country
+type Geography map[string]Country
 
 type Country struct {
 	Name      string

From 3ef6473c8b065be189f6512bf35f753865edb595 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 14:38:41 +0530
Subject: [PATCH 11/26] update: Distributors interface signature

---
 store/store.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/store/store.go b/store/store.go
index bc77fe9f5..10a85abd6 100644
--- a/store/store.go
+++ b/store/store.go
@@ -3,7 +3,7 @@ package store
 import "challenge2016/models"
 
 type Distributors interface {
-	Insert(models.Distributor) error
-	Exists(name string) (bool, error)
-	CheckPermission(distributor string, region models.Region) (bool, error)
+	Insert(distributor models.Distributor, parentName string) error
+	Exists(name string) bool
+	CheckAuthorization(distributor string, region models.Region) (bool, error)
 }

From f0991de0b526cb5a7e3c8ca626f7369c7e82a4e8 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 14:43:39 +0530
Subject: [PATCH 12/26] update: ValidateIncludedRegions and
 ValidateExcludedRegions in Distributor

---
 models/distributor.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/models/distributor.go b/models/distributor.go
index 3f6576cee..67f8ba061 100644
--- a/models/distributor.go
+++ b/models/distributor.go
@@ -48,6 +48,16 @@ func (d Distributor) ValidateRegion(region Region) bool {
 	return false
 }
 
+// ValidateIncludedRegions returns true if the region is authorized for the distributor.
+func (d Distributor) ValidateIncludedRegions(region Region) bool {
+	return validateRegion(region, d.IncludeRegions)
+}
+
+// ValidateExcludedRegions returns true if the region is authorized for the distributor.
+func (d Distributor) ValidateExcludedRegions(region Region) bool {
+	return validateRegion(region, d.ExcludedRegions)
+}
+
 func validateRegion(region Region, regions []Region) bool {
 	for _, r := range regions {
 		// Exact match.

From ca093b70ab558aa32caf54b0a0c8ca7c7f1fa480 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 14:44:14 +0530
Subject: [PATCH 13/26] add: implement Distributors store

---
 store/distributor.go | 84 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 store/distributor.go

diff --git a/store/distributor.go b/store/distributor.go
new file mode 100644
index 000000000..f992d4ac4
--- /dev/null
+++ b/store/distributor.go
@@ -0,0 +1,84 @@
+package store
+
+import (
+	"errors"
+
+	"challenge2016/models"
+)
+
+type distributors struct {
+	list map[string]models.Distributor
+}
+
+// NewDistributors returns a new instance of Distributors.
+func NewDistributors(all models.Geography) Distributors {
+	return &distributors{
+		list: make(map[string]models.Distributor),
+	}
+}
+
+// Insert inserts a new distributor.
+func (d *distributors) Insert(distributor models.Distributor, parentName string) error {
+	if _, exists := d.list[distributor.Name]; exists {
+		return errors.New("distributor already exists")
+	}
+
+	if parentName == "" {
+		d.list[distributor.Name] = distributor
+		return nil
+	}
+
+	parent, exists := d.list[parentName]
+	if !exists {
+		return errors.New("parent distributor does not exist")
+	}
+
+	allowed := false
+
+	for _, region := range distributor.IncludeRegions {
+		if parent.ValidateIncludedRegions(region) {
+			allowed = true
+			break
+		}
+	}
+
+	if !allowed {
+		return errors.New("parent distributor does not allow this distributor")
+	}
+
+	for _, region := range distributor.ExcludedRegions {
+		if parent.ValidateExcludedRegions(region) {
+			allowed = false
+			break
+		}
+	}
+
+	if !allowed {
+		return errors.New("parent distributor does not allow this distributor")
+	}
+
+	d.list[distributor.Name] = distributor
+
+	return nil
+}
+
+// Exists returns true if the distributor exists.
+func (d *distributors) Exists(name string) bool {
+	_, exists := d.list[name]
+
+	return exists
+}
+
+// CheckAuthorization returns true if the region is authorized for the distributor.
+func (d *distributors) CheckAuthorization(distributor string, region models.Region) (bool, error) {
+	parent, exists := d.list[distributor]
+	if !exists {
+		return false, errors.New("parent distributor does not exist")
+	}
+
+	if !parent.ValidateRegion(region) {
+		return false, nil
+	}
+
+	return true, nil
+}

From ee55ea5520170dcadc19accbb785259b1f8d1ce8 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 15:03:23 +0530
Subject: [PATCH 14/26] add: Validate in Geography

---
 models/geography.go | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/models/geography.go b/models/geography.go
index 49f0c2288..59fc0ee6a 100644
--- a/models/geography.go
+++ b/models/geography.go
@@ -17,3 +17,35 @@ type Province struct {
 }
 
 type Cities map[string]string
+
+// Validate checks whether the region is valid.
+func (g Geography) Validate(r Region) bool {
+	if r.CountryCode == "" {
+		return false
+	}
+
+	_, exists := g[r.CountryCode]
+	if !exists {
+		return false
+	}
+
+	if r.ProvinceCode == "" {
+		return true
+	}
+
+	_, exists = g[r.CountryCode].Provinces[r.ProvinceCode]
+	if !exists {
+		return false
+	}
+
+	if r.CityCode == "" {
+		return true
+	}
+
+	_, exists = g[r.CountryCode].Provinces[r.ProvinceCode].Cities[r.CityCode]
+	if !exists {
+		return false
+	}
+
+	return true
+}

From 0ebdaf67d42828456fc89a8c5da31c472c8c1f0b Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 15:05:31 +0530
Subject: [PATCH 15/26] update: validate whether Region exists in Geography

---
 store/distributor.go | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/store/distributor.go b/store/distributor.go
index f992d4ac4..c734b4cb6 100644
--- a/store/distributor.go
+++ b/store/distributor.go
@@ -7,13 +7,15 @@ import (
 )
 
 type distributors struct {
-	list map[string]models.Distributor
+	list      map[string]models.Distributor
+	geography models.Geography
 }
 
 // NewDistributors returns a new instance of Distributors.
 func NewDistributors(all models.Geography) Distributors {
 	return &distributors{
-		list: make(map[string]models.Distributor),
+		list:      make(map[string]models.Distributor),
+		geography: all,
 	}
 }
 
@@ -36,6 +38,10 @@ func (d *distributors) Insert(distributor models.Distributor, parentName string)
 	allowed := false
 
 	for _, region := range distributor.IncludeRegions {
+		if !d.geography.Validate(region) {
+			return errors.New("invalid region")
+		}
+
 		if parent.ValidateIncludedRegions(region) {
 			allowed = true
 			break
@@ -47,6 +53,10 @@ func (d *distributors) Insert(distributor models.Distributor, parentName string)
 	}
 
 	for _, region := range distributor.ExcludedRegions {
+		if !d.geography.Validate(region) {
+			return errors.New("invalid region")
+		}
+
 		if parent.ValidateExcludedRegions(region) {
 			allowed = false
 			break

From 372cd2d82702b084bc83741e43beed69a74cacfa Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 15:12:49 +0530
Subject: [PATCH 16/26] fix: set parent in Distributors store Insert

---
 store/distributor.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/store/distributor.go b/store/distributor.go
index c734b4cb6..47fe886f4 100644
--- a/store/distributor.go
+++ b/store/distributor.go
@@ -67,6 +67,8 @@ func (d *distributors) Insert(distributor models.Distributor, parentName string)
 		return errors.New("parent distributor does not allow this distributor")
 	}
 
+	distributor.Parent = &parent
+
 	d.list[distributor.Name] = distributor
 
 	return nil

From ab2e32f12352c1d90e9003c10e8dc6d7c4c4ddaf Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 16:05:38 +0530
Subject: [PATCH 17/26] add: Get by name in Distributors store

---
 store/distributor.go | 10 ++++++++++
 store/store.go       |  1 +
 2 files changed, 11 insertions(+)

diff --git a/store/distributor.go b/store/distributor.go
index 47fe886f4..9adef1c8b 100644
--- a/store/distributor.go
+++ b/store/distributor.go
@@ -94,3 +94,13 @@ func (d *distributors) CheckAuthorization(distributor string, region models.Regi
 
 	return true, nil
 }
+
+// Get returns the distributor.
+func (d *distributors) Get(name string) (models.Distributor, error) {
+	distributor, exists := d.list[name]
+	if !exists {
+		return models.Distributor{}, errors.New("distributor does not exist")
+	}
+
+	return distributor, nil
+}
diff --git a/store/store.go b/store/store.go
index 10a85abd6..e5fdc2683 100644
--- a/store/store.go
+++ b/store/store.go
@@ -5,5 +5,6 @@ import "challenge2016/models"
 type Distributors interface {
 	Insert(distributor models.Distributor, parentName string) error
 	Exists(name string) bool
+	Get(name string) (models.Distributor, error)
 	CheckAuthorization(distributor string, region models.Region) (bool, error)
 }

From 881d9c048dc5c456bfa299b250f52d38e86d10fb Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 16:09:16 +0530
Subject: [PATCH 18/26] update: add parent in Distributor Stringer

---
 models/distributor.go | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/models/distributor.go b/models/distributor.go
index 67f8ba061..dced70a00 100644
--- a/models/distributor.go
+++ b/models/distributor.go
@@ -18,9 +18,15 @@ func NewDistributor(name string, includeRegions []Region, excludedRegions []Regi
 
 // String returns a string representation of the distributor.
 func (d Distributor) String() string {
-	res := "Name: " + d.Name + "\n"
+	res := "Name: " + d.Name
 
-	res += "INCLUDE:"
+	parent := d.Parent
+	for parent != nil {
+		res += " > " + parent.Name
+		parent = parent.Parent
+	}
+
+	res += "\nINCLUDE:"
 	for _, region := range d.IncludeRegions {
 		res += region.String() + "\n"
 	}

From 8582d1f592c192a4292d5f85683db0d755a94337 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 18:33:11 +0530
Subject: [PATCH 19/26] update: return Distributor pointer

---
 models/distributor.go | 10 ++++++++--
 store/distributor.go  | 10 +++++++---
 store/store.go        |  2 +-
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/models/distributor.go b/models/distributor.go
index dced70a00..54bcedfb2 100644
--- a/models/distributor.go
+++ b/models/distributor.go
@@ -26,12 +26,18 @@ func (d Distributor) String() string {
 		parent = parent.Parent
 	}
 
-	res += "\nINCLUDE:"
+	if len(d.IncludeRegions) == 0 {
+		res += "\nINCLUDE:"
+	}
+
 	for _, region := range d.IncludeRegions {
 		res += region.String() + "\n"
 	}
 
-	res += "EXCLUDE: "
+	if len(d.ExcludedRegions) == 0 {
+		res += "EXCLUDE: "
+	}
+
 	for _, region := range d.ExcludedRegions {
 		res += region.String() + "\n"
 	}
diff --git a/store/distributor.go b/store/distributor.go
index 9adef1c8b..0c3c663f6 100644
--- a/store/distributor.go
+++ b/store/distributor.go
@@ -96,11 +96,15 @@ func (d *distributors) CheckAuthorization(distributor string, region models.Regi
 }
 
 // Get returns the distributor.
-func (d *distributors) Get(name string) (models.Distributor, error) {
+func (d *distributors) Get(name string) (*models.Distributor, error) {
+	if name == "" {
+		return nil, errors.New("distributor name is required")
+	}
+
 	distributor, exists := d.list[name]
 	if !exists {
-		return models.Distributor{}, errors.New("distributor does not exist")
+		return nil, errors.New("distributor does not exist")
 	}
 
-	return distributor, nil
+	return &distributor, nil
 }
diff --git a/store/store.go b/store/store.go
index e5fdc2683..994d2efcf 100644
--- a/store/store.go
+++ b/store/store.go
@@ -5,6 +5,6 @@ import "challenge2016/models"
 type Distributors interface {
 	Insert(distributor models.Distributor, parentName string) error
 	Exists(name string) bool
-	Get(name string) (models.Distributor, error)
+	Get(name string) (*models.Distributor, error)
 	CheckAuthorization(distributor string, region models.Region) (bool, error)
 }

From e54655c19c80fbc98c9d38c3075b88fd62b2bd69 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 18:33:44 +0530
Subject: [PATCH 20/26] add: cobra cli for commands

---
 cmd/cli.go | 116 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 go.mod     |   6 +++
 go.sum     |  10 +++++
 main.go    |  18 +++++++++
 4 files changed, 150 insertions(+)
 create mode 100644 cmd/cli.go
 create mode 100644 go.sum

diff --git a/cmd/cli.go b/cmd/cli.go
new file mode 100644
index 000000000..9234dac52
--- /dev/null
+++ b/cmd/cli.go
@@ -0,0 +1,116 @@
+package cmd
+
+import (
+	"challenge2016/models"
+	"challenge2016/store"
+
+	"github.com/spf13/cobra"
+)
+
+type CLI struct {
+	cmd   *cobra.Command
+	store store.Distributors
+}
+
+func NewCLI(store store.Distributors) *CLI {
+	rootCmd := &cobra.Command{
+		Use:   "challenge2016",
+		Short: "A CLI tool to manage distributors",
+	}
+
+	return &CLI{
+		cmd:   rootCmd,
+		store: store,
+	}
+}
+
+func (c *CLI) Init() error {
+	distributorCmd := &cobra.Command{
+		Use:   "distributors",
+		Short: "Manage distributors",
+	}
+
+	var (
+		name, parent     string
+		include, exclude []string
+	)
+
+	addDistributorCmd := &cobra.Command{
+		Use:   "add",
+		Short: "Get a distributor",
+		Run: func(cmd *cobra.Command, args []string) {
+			var includes, excludes []models.Region
+
+			for _, v := range include {
+				includes = append(includes, models.Parse(v))
+			}
+
+			for _, v := range exclude {
+				excludes = append(excludes, models.Parse(v))
+			}
+
+			dist := models.NewDistributor(name, includes, excludes)
+
+			err := c.store.Insert(dist, parent)
+			if err != nil {
+				println(err.Error())
+
+				return
+			}
+
+			distributor, err := c.store.Get(name)
+			if err != nil {
+				println(err.Error())
+
+				return
+			}
+
+			if distributor == nil {
+				println("Distributor does not exist")
+				return
+			}
+
+			println(distributor.String())
+		},
+	}
+
+	addDistributorCmd.Flags().StringVarP(&name, "name", "n", "", "Distributor name")
+	addDistributorCmd.Flags().StringSliceVarP(&include, "include", "i", []string{}, "Include regions")
+	addDistributorCmd.Flags().StringSliceVarP(&exclude, "exclude", "e", []string{}, "Exclude regions")
+	addDistributorCmd.Flags().StringVarP(&parent, "parent", "p", "", "Parent distributor name")
+
+	err := addDistributorCmd.MarkFlagRequired("name")
+	if err != nil {
+		return err
+	}
+
+	getDistributorCmd := &cobra.Command{
+		Use:   "get",
+		Short: "Get a distributor",
+		Args:  cobra.ExactArgs(1),
+		Run: func(cmd *cobra.Command, args []string) {
+			distributor, err := c.store.Get(args[0])
+			if err != nil {
+				println(err.Error())
+
+				return
+			}
+
+			println(distributor.String())
+		},
+	}
+
+	c.cmd.AddCommand(distributorCmd)
+	distributorCmd.AddCommand(addDistributorCmd, getDistributorCmd)
+
+	return nil
+}
+
+func (c *CLI) Run() error {
+	err := c.cmd.Execute()
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
diff --git a/go.mod b/go.mod
index 8e4ec9e65..89e6747d5 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,9 @@
 module challenge2016
 
 go 1.23.1
+
+require (
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/spf13/cobra v1.8.1 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 000000000..912390a78
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,10 @@
+github.com/cpuguy83/go-md2man/v2 v2.0.4/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
+github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
+github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/spf13/cobra v1.8.1 h1:e5/vxKd/rZsfSJMUX1agtjeTDf+qv1/JdBF8gg5k9ZM=
+github.com/spf13/cobra v1.8.1/go.mod h1:wHxEcudfqmLYa8iTfL+OuZPbBZkmvliBWKIezN3kD9Y=
+github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
+github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/main.go b/main.go
index 790580777..66493f429 100644
--- a/main.go
+++ b/main.go
@@ -1,5 +1,23 @@
 package main
 
+import (
+	"challenge2016/cmd"
+	"challenge2016/csv"
+	"challenge2016/store"
+)
+
 func main() {
+	geography, err := csv.Load("./cities.csv")
+	if err != nil {
+		panic(err)
+	}
+
+	distStore := store.NewDistributors(geography)
+
+	cli := cmd.NewCLI(distStore)
+	if err = cli.Init(); err != nil {
+		panic(err)
+	}
 
+	cli.Run()
 }

From 99c94e5768938605bcc495b549f5a2b6fa58279e Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 19:05:01 +0530
Subject: [PATCH 21/26] remove: cli

---
 cmd/cli.go | 116 -----------------------------------------------------
 1 file changed, 116 deletions(-)
 delete mode 100644 cmd/cli.go

diff --git a/cmd/cli.go b/cmd/cli.go
deleted file mode 100644
index 9234dac52..000000000
--- a/cmd/cli.go
+++ /dev/null
@@ -1,116 +0,0 @@
-package cmd
-
-import (
-	"challenge2016/models"
-	"challenge2016/store"
-
-	"github.com/spf13/cobra"
-)
-
-type CLI struct {
-	cmd   *cobra.Command
-	store store.Distributors
-}
-
-func NewCLI(store store.Distributors) *CLI {
-	rootCmd := &cobra.Command{
-		Use:   "challenge2016",
-		Short: "A CLI tool to manage distributors",
-	}
-
-	return &CLI{
-		cmd:   rootCmd,
-		store: store,
-	}
-}
-
-func (c *CLI) Init() error {
-	distributorCmd := &cobra.Command{
-		Use:   "distributors",
-		Short: "Manage distributors",
-	}
-
-	var (
-		name, parent     string
-		include, exclude []string
-	)
-
-	addDistributorCmd := &cobra.Command{
-		Use:   "add",
-		Short: "Get a distributor",
-		Run: func(cmd *cobra.Command, args []string) {
-			var includes, excludes []models.Region
-
-			for _, v := range include {
-				includes = append(includes, models.Parse(v))
-			}
-
-			for _, v := range exclude {
-				excludes = append(excludes, models.Parse(v))
-			}
-
-			dist := models.NewDistributor(name, includes, excludes)
-
-			err := c.store.Insert(dist, parent)
-			if err != nil {
-				println(err.Error())
-
-				return
-			}
-
-			distributor, err := c.store.Get(name)
-			if err != nil {
-				println(err.Error())
-
-				return
-			}
-
-			if distributor == nil {
-				println("Distributor does not exist")
-				return
-			}
-
-			println(distributor.String())
-		},
-	}
-
-	addDistributorCmd.Flags().StringVarP(&name, "name", "n", "", "Distributor name")
-	addDistributorCmd.Flags().StringSliceVarP(&include, "include", "i", []string{}, "Include regions")
-	addDistributorCmd.Flags().StringSliceVarP(&exclude, "exclude", "e", []string{}, "Exclude regions")
-	addDistributorCmd.Flags().StringVarP(&parent, "parent", "p", "", "Parent distributor name")
-
-	err := addDistributorCmd.MarkFlagRequired("name")
-	if err != nil {
-		return err
-	}
-
-	getDistributorCmd := &cobra.Command{
-		Use:   "get",
-		Short: "Get a distributor",
-		Args:  cobra.ExactArgs(1),
-		Run: func(cmd *cobra.Command, args []string) {
-			distributor, err := c.store.Get(args[0])
-			if err != nil {
-				println(err.Error())
-
-				return
-			}
-
-			println(distributor.String())
-		},
-	}
-
-	c.cmd.AddCommand(distributorCmd)
-	distributorCmd.AddCommand(addDistributorCmd, getDistributorCmd)
-
-	return nil
-}
-
-func (c *CLI) Run() error {
-	err := c.cmd.Execute()
-	if err != nil {
-		return err
-	}
-
-	return nil
-}

From 0dc2782ba9c1010ea2145244bce978cefe81dcd3 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 19:05:32 +0530
Subject: [PATCH 22/26] fix: format of Region String

---
 models/distributor.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/models/distributor.go b/models/distributor.go
index 54bcedfb2..35326271a 100644
--- a/models/distributor.go
+++ b/models/distributor.go
@@ -26,7 +26,7 @@ func (d Distributor) String() string {
 		parent = parent.Parent
 	}
 
-	if len(d.IncludeRegions) == 0 {
+	if len(d.IncludeRegions) != 0 {
 		res += "\nINCLUDE:"
 	}
 
@@ -34,7 +34,7 @@ func (d Distributor) String() string {
 		res += region.String() + "\n"
 	}
 
-	if len(d.ExcludedRegions) == 0 {
+	if len(d.ExcludedRegions) != 0 {
 		res += "EXCLUDE: "
 	}
 

From 437f591d027779fc01aee6e5b2ef5a0695669d51 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 19:06:07 +0530
Subject: [PATCH 23/26] add: handler for distributor HTTP APIs

---
 dto/distributor.go     |  8 ++++
 dto/region.go          |  5 +++
 go.mod                 | 31 ++++++++++++--
 go.sum                 | 92 ++++++++++++++++++++++++++++++++++++++----
 handler/distributor.go | 90 +++++++++++++++++++++++++++++++++++++++++
 main.go                | 23 ++++++++---
 6 files changed, 232 insertions(+), 17 deletions(-)
 create mode 100644 dto/distributor.go
 create mode 100644 dto/region.go
 create mode 100644 handler/distributor.go

diff --git a/dto/distributor.go b/dto/distributor.go
new file mode 100644
index 000000000..340e876ab
--- /dev/null
+++ b/dto/distributor.go
@@ -0,0 +1,8 @@
+package dto
+
+type Distributor struct {
+	Name            string   `json:"name,omitempty"`
+	Parent          string   `json:"parent,omitempty"`
+	IncludeRegions  []string `json:"include,omitempty"`
+	ExcludedRegions []string `json:"exclude,omitempty"`
+}
diff --git a/dto/region.go b/dto/region.go
new file mode 100644
index 000000000..d88ab0814
--- /dev/null
+++ b/dto/region.go
@@ -0,0 +1,5 @@
+package dto
+
+type Region struct {
+	Region string `json:"region,omitempty"`
+}
diff --git a/go.mod b/go.mod
index 89e6747d5..12d09c1fd 100644
--- a/go.mod
+++ b/go.mod
@@ -2,8 +2,33 @@ module challenge2016
 
 go 1.23.1
 
+require github.com/gin-gonic/gin v1.10.0
+
 require (
-	github.com/inconshreveable/mousetrap v1.1.0 // indirect
-	github.com/spf13/cobra v1.8.1 // indirect
-	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/bytedance/sonic v1.12.3 // indirect
+	github.com/bytedance/sonic/loader v0.2.1 // indirect
+	github.com/cloudwego/base64x v0.1.4 // indirect
+	github.com/cloudwego/iasm v0.2.0 // indirect
+	github.com/gabriel-vasile/mimetype v1.4.6 // indirect
+	github.com/gin-contrib/sse v0.1.0 // indirect
+	github.com/go-playground/locales v0.14.1 // indirect
+	github.com/go-playground/universal-translator v0.18.1 // indirect
+	github.com/go-playground/validator/v10 v10.22.1 // indirect
+	github.com/goccy/go-json v0.10.3 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/klauspost/cpuid/v2 v2.2.8 // indirect
+	github.com/leodido/go-urn v1.4.0 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.3 // indirect
+	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
+	github.com/ugorji/go/codec v1.2.12 // indirect
+	golang.org/x/arch v0.11.0 // indirect
+	golang.org/x/crypto v0.28.0 // indirect
+	golang.org/x/net v0.30.0 // indirect
+	golang.org/x/sys v0.26.0 // indirect
+	golang.org/x/text v0.19.0 // indirect
+	google.golang.org/protobuf v1.35.1 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
diff --git a/go.sum b/go.sum
index 912390a78..fd90bcf71 100644
--- a/go.sum
+++ b/go.sum
@@ -1,10 +1,86 @@
-github.com/cpuguy83/go-md2man/v2 v2.0.4/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
-github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
-github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
-github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
-github.com/spf13/cobra v1.8.1 h1:e5/vxKd/rZsfSJMUX1agtjeTDf+qv1/JdBF8gg5k9ZM=
-github.com/spf13/cobra v1.8.1/go.mod h1:wHxEcudfqmLYa8iTfL+OuZPbBZkmvliBWKIezN3kD9Y=
-github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
-github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/bytedance/sonic v1.12.3 h1:W2MGa7RCU1QTeYRTPE3+88mVC0yXmsRQRChiyVocVjU=
+github.com/bytedance/sonic v1.12.3/go.mod h1:B8Gt/XvtZ3Fqj+iSKMypzymZxw/FVwgIGKzMzT9r/rk=
+github.com/bytedance/sonic/loader v0.1.1/go.mod h1:ncP89zfokxS5LZrJxl5z0UJcsk4M4yY2JpfqGeCtNLU=
+github.com/bytedance/sonic/loader v0.2.1 h1:1GgorWTqf12TA8mma4DDSbaQigE2wOgQo7iCjjJv3+E=
+github.com/bytedance/sonic/loader v0.2.1/go.mod h1:ncP89zfokxS5LZrJxl5z0UJcsk4M4yY2JpfqGeCtNLU=
+github.com/cloudwego/base64x v0.1.4 h1:jwCgWpFanWmN8xoIUHa2rtzmkd5J2plF/dnLS6Xd/0Y=
+github.com/cloudwego/base64x v0.1.4/go.mod h1:0zlkT4Wn5C6NdauXdJRhSKRlJvmclQ1hhJgA0rcu/8w=
+github.com/cloudwego/iasm v0.2.0 h1:1KNIy1I1H9hNNFEEH3DVnI4UujN+1zjpuk6gwHLTssg=
+github.com/cloudwego/iasm v0.2.0/go.mod h1:8rXZaNYT2n95jn+zTI1sDr+IgcD2GVs0nlbbQPiEFhY=
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diff --git a/handler/distributor.go b/handler/distributor.go
new file mode 100644
index 000000000..cec3823ff
--- /dev/null
+++ b/handler/distributor.go
@@ -0,0 +1,90 @@
+package handler
+
+import (
+	"challenge2016/dto"
+	"challenge2016/models"
+	"challenge2016/store"
+
+	"github.com/gin-gonic/gin"
+)
+
+type Distributor struct {
+	store store.Distributors
+}
+
+// NewDistributor returns a new instance of Distributor.
+func NewDistributor(store store.Distributors) *Distributor {
+	return &Distributor{
+		store: store,
+	}
+}
+
+// Get returns the distributor.
+func (d *Distributor) Get(c *gin.Context) {
+	name := c.Param("name")
+	dist, err := d.store.Get(name)
+	if err != nil {
+		c.JSON(404, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(200, dist)
+}
+
+// Insert inserts a new distributor.
+func (d *Distributor) Insert(c *gin.Context) {
+	var distributor dto.Distributor
+
+	err := c.BindJSON(&distributor)
+	if err != nil {
+		c.JSON(400, gin.H{"error": err.Error()})
+	}
+
+	var includes, excludes []models.Region
+
+	for _, region := range distributor.IncludeRegions {
+		includes = append(includes, models.Parse(region))
+	}
+
+	for _, region := range distributor.ExcludedRegions {
+		excludes = append(excludes, models.Parse(region))
+	}
+
+	model := models.Distributor{
+		Name:            distributor.Name,
+		IncludeRegions:  includes,
+		ExcludedRegions: excludes,
+	}
+
+	err = d.store.Insert(model, distributor.Parent)
+	if err != nil {
+		c.JSON(400, gin.H{"error": err.Error()})
+		return
+	}
+
+	created, err := d.store.Get(distributor.Name)
+	if err != nil {
+		c.JSON(400, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(201, created)
+}
+
+// Authorization checks whether a distributor is allowed to access a region.
+func (d *Distributor) Authorization(c *gin.Context) {
+	distributor := c.Param("name")
+
+	var region dto.Region
+	err := c.BindJSON(&region)
+	if err != nil {
+		c.JSON(400, gin.H{"error": err.Error()})
+	}
+
+	allowed, err := d.store.CheckAuthorization(distributor, models.Parse(region.Region))
+	if err != nil {
+		c.JSON(400, gin.H{"error": err.Error()})
+	}
+
+	c.JSON(200, gin.H{"allowed": allowed})
+}
diff --git a/main.go b/main.go
index 66493f429..63bcb7de2 100644
--- a/main.go
+++ b/main.go
@@ -1,9 +1,13 @@
 package main
 
 import (
-	"challenge2016/cmd"
+	"log/slog"
+
 	"challenge2016/csv"
+	"challenge2016/handler"
 	"challenge2016/store"
+
+	"github.com/gin-gonic/gin"
 )
 
 func main() {
@@ -14,10 +18,17 @@ func main() {
 
 	distStore := store.NewDistributors(geography)
 
-	cli := cmd.NewCLI(distStore)
-	if err = cli.Init(); err != nil {
-		panic(err)
-	}
+	distributorHandler := handler.NewDistributor(distStore)
 
-	cli.Run()
+	router := gin.Default()
+
+	router.GET("/distributors/:name", distributorHandler.Get)
+	router.POST("/distributors", distributorHandler.Insert)
+	router.POST("/distributors/:name/authorization", distributorHandler.Authorization)
+
+	err = router.Run(":8080")
+	if err != nil {
+		slog.Error(err.Error())
+		return
+	}
 }

From 1573411f45a3be5c594385cfe36fdcd3bdaae8f5 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 19:23:02 +0530
Subject: [PATCH 24/26] add: ModelToDTO for Distributor

---
 dto/distributor.go | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/dto/distributor.go b/dto/distributor.go
index 340e876ab..e2e1ecba2 100644
--- a/dto/distributor.go
+++ b/dto/distributor.go
@@ -1,8 +1,36 @@
 package dto
 
+import "challenge2016/models"
+
 type Distributor struct {
 	Name            string   `json:"name,omitempty"`
 	Parent          string   `json:"parent,omitempty"`
 	IncludeRegions  []string `json:"include,omitempty"`
 	ExcludedRegions []string `json:"exclude,omitempty"`
 }
+
+func ModelToDTO(d models.Distributor) Distributor {
+	var (
+		includesStr, excludesStr []string
+	)
+
+	for _, region := range d.IncludeRegions {
+		includesStr = append(includesStr, region.String())
+	}
+
+	for _, region := range d.ExcludedRegions {
+		excludesStr = append(excludesStr, region.String())
+	}
+
+	resp := Distributor{
+		Name:            d.Name,
+		IncludeRegions:  includesStr,
+		ExcludedRegions: excludesStr,
+	}
+
+	if d.Parent != nil {
+		resp.Parent = d.Parent.Name
+	}
+
+	return resp
+}

From 16d75f3c827883fe415c8edbc47b247e4b3847d3 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 19:23:24 +0530
Subject: [PATCH 25/26] fix: return on error in handler

---
 handler/distributor.go | 33 ++++++++++++++++++++++++---------
 store/distributor.go   |  5 +++--
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/handler/distributor.go b/handler/distributor.go
index cec3823ff..6deff99dc 100644
--- a/handler/distributor.go
+++ b/handler/distributor.go
@@ -1,6 +1,8 @@
 package handler
 
 import (
+	"net/http"
+
 	"challenge2016/dto"
 	"challenge2016/models"
 	"challenge2016/store"
@@ -24,11 +26,16 @@ func (d *Distributor) Get(c *gin.Context) {
 	name := c.Param("name")
 	dist, err := d.store.Get(name)
 	if err != nil {
-		c.JSON(404, gin.H{"error": err.Error()})
+		c.JSON(http.StatusNotFound, gin.H{"error": err.Error()})
 		return
 	}
 
-	c.JSON(200, dist)
+	if dist == nil {
+		c.JSON(http.StatusNotFound, gin.H{"error": "distributor not found"})
+		return
+	}
+
+	c.JSON(http.StatusOK, dto.ModelToDTO(*dist))
 }
 
 // Insert inserts a new distributor.
@@ -37,7 +44,7 @@ func (d *Distributor) Insert(c *gin.Context) {
 
 	err := c.BindJSON(&distributor)
 	if err != nil {
-		c.JSON(400, gin.H{"error": err.Error()})
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 	}
 
 	var includes, excludes []models.Region
@@ -58,17 +65,22 @@ func (d *Distributor) Insert(c *gin.Context) {
 
 	err = d.store.Insert(model, distributor.Parent)
 	if err != nil {
-		c.JSON(400, gin.H{"error": err.Error()})
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 		return
 	}
 
 	created, err := d.store.Get(distributor.Name)
 	if err != nil {
-		c.JSON(400, gin.H{"error": err.Error()})
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	if created == nil {
+		c.JSON(http.StatusNotFound, gin.H{"error": "distributor not found"})
 		return
 	}
 
-	c.JSON(201, created)
+	c.JSON(http.StatusCreated, dto.ModelToDTO(*created))
 }
 
 // Authorization checks whether a distributor is allowed to access a region.
@@ -76,15 +88,18 @@ func (d *Distributor) Authorization(c *gin.Context) {
 	distributor := c.Param("name")
 
 	var region dto.Region
+
 	err := c.BindJSON(&region)
 	if err != nil {
-		c.JSON(400, gin.H{"error": err.Error()})
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
 	}
 
 	allowed, err := d.store.CheckAuthorization(distributor, models.Parse(region.Region))
 	if err != nil {
-		c.JSON(400, gin.H{"error": err.Error()})
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
 	}
 
-	c.JSON(200, gin.H{"allowed": allowed})
+	c.JSON(http.StatusOK, gin.H{"allowed": allowed})
 }
diff --git a/store/distributor.go b/store/distributor.go
index 0c3c663f6..55fa7ad23 100644
--- a/store/distributor.go
+++ b/store/distributor.go
@@ -21,7 +21,8 @@ func NewDistributors(all models.Geography) Distributors {
 
 // Insert inserts a new distributor.
 func (d *distributors) Insert(distributor models.Distributor, parentName string) error {
-	if _, exists := d.list[distributor.Name]; exists {
+	_, exists := d.list[distributor.Name]
+	if exists {
 		return errors.New("distributor already exists")
 	}
 
@@ -85,7 +86,7 @@ func (d *distributors) Exists(name string) bool {
 func (d *distributors) CheckAuthorization(distributor string, region models.Region) (bool, error) {
 	parent, exists := d.list[distributor]
 	if !exists {
-		return false, errors.New("parent distributor does not exist")
+		return false, errors.New("distributor does not exist")
 	}
 
 	if !parent.ValidateRegion(region) {

From 5ae909fde76ca309732f46f6a6857439c1150388 Mon Sep 17 00:00:00 2001
From: Sreeram Narayanan <sreeram.an1994@gmail.com>
Date: Tue, 29 Oct 2024 20:21:44 +0530
Subject: [PATCH 26/26] add: OpenAPI spec

---
 openapi.yaml | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 openapi.yaml

diff --git a/openapi.yaml b/openapi.yaml
new file mode 100644
index 000000000..b9cb8c958
--- /dev/null
+++ b/openapi.yaml
@@ -0,0 +1,96 @@
+openapi: 3.1.0
+info:
+  title: Title
+  description: Title
+  version: 1.0.0
+servers:
+  - url: 'http://localhost:8080'
+paths:
+  /distributors/{name}:
+    get:
+      summary: Get a distributor by name.
+      description: Description
+      operationId: OperationId
+      parameters:
+        - name: name
+          in: query
+          required: true
+          schema:
+            type: string
+          description: Description
+      responses:
+        '200':
+          description: Description
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Distributor'
+  /distributors:
+    post:
+      summary: Create a new distributor.
+      description: Description
+      operationId: OperationId
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/Distributor'
+      responses:
+        '200':
+          description: Description
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Distributor'
+  /distributors/{name}/authorization:
+    post:
+      summary: Check if a distributor is allowed to access a region.
+      description: Description
+      operationId: OperationId
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/Region'
+      responses:
+        '200':
+          description: Description
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Authorization'
+components:
+  schemas:
+    Distributor:
+      type: object
+      properties:
+        name:
+          type: string
+        parent:
+          type: string
+        include:
+          type: array
+          items:
+            type: string
+        exclude:
+          type: array
+          items:
+            type: string
+      required:
+        - name
+    Authorization:
+      type: object
+      properties:
+        allowed:
+          type: boolean
+      required:
+        - allowed
+    Region:
+      type: object
+      properties:
+        region:
+          type: string
+      required:
+        - region