package region

import (
	"os"
	"path/filepath"
	"testing"
)

func TestDefaultConfig(t *testing.T) {
	cfg := DefaultConfig()
	if len(cfg.Regions) != 2 {
		t.Fatalf("expected 2 default regions, got %d", len(cfg.Regions))
	}

	if got := cfg.CurrencyOf("se"); got != "SEK" {
		t.Errorf("CurrencyOf(se) = %s, want SEK", got)
	}
	if got := cfg.LocaleOf("se"); got != "sv-se" {
		t.Errorf("LocaleOf(se) = %s, want sv-se", got)
	}
	if got := cfg.CurrencyOf("no"); got != "NOK" {
		t.Errorf("CurrencyOf(no) = %s, want NOK", got)
	}
	if got := cfg.LocaleOf("no"); got != "nb-no" {
		t.Errorf("LocaleOf(no) = %s, want nb-no", got)
	}
}

func TestCurrencyOf(t *testing.T) {
	cfg := DefaultConfig()

	tests := []struct {
		country string
		want    string
	}{
		{"se", "SEK"},
		{"SE", "SEK"},
		{"no", "NOK"},
		{"NO", "NOK"},
		{"dk", "SEK"},   // unknown → default
		{"fi", "SEK"},   // unknown → default
		{"us", "SEK"},   // unknown → default
		{"", "SEK"},     // empty → default
	}
	for _, tt := range tests {
		t.Run(tt.country, func(t *testing.T) {
			if got := cfg.CurrencyOf(tt.country); got != tt.want {
				t.Errorf("CurrencyOf(%q) = %q, want %q", tt.country, got, tt.want)
			}
		})
	}
}

func TestLocaleOf(t *testing.T) {
	cfg := DefaultConfig()

	tests := []struct {
		country string
		want    string
	}{
		{"se", "sv-se"},
		{"SE", "sv-se"},
		{"no", "nb-no"},
		{"NO", "nb-no"},
		{"dk", "sv-se"},  // unknown → default
		{"", "sv-se"},    // empty → default
	}
	for _, tt := range tests {
		t.Run(tt.country, func(t *testing.T) {
			if got := cfg.LocaleOf(tt.country); got != tt.want {
				t.Errorf("LocaleOf(%q) = %q, want %q", tt.country, got, tt.want)
			}
		})
	}
}

func TestCountryFromCurrency(t *testing.T) {
	cfg := DefaultConfig()

	tests := []struct {
		currency string
		want    string
	}{
		{"SEK", "se"},
		{"sek", "se"},
		{"NOK", "no"},
		{"nok", "no"},
		{"DKK", "se"},   // unknown → default
		{"EUR", "se"},   // unknown → default
		{"", "se"},      // empty → default
	}
	for _, tt := range tests {
		t.Run(tt.currency, func(t *testing.T) {
			if got := cfg.CountryFromCurrency(tt.currency); got != tt.want {
				t.Errorf("CountryFromCurrency(%q) = %q, want %q", tt.currency, got, tt.want)
			}
		})
	}
}

func TestLoadConfig_FileNotFound(t *testing.T) {
	cfg, err := LoadConfig("/nonexistent/regions.json")
	if err != nil {
		t.Fatalf("LoadConfig on missing file should not error: %v", err)
	}
	if cfg == nil {
		t.Fatal("expected non-nil config on missing file")
	}
	if len(cfg.Regions) != 2 {
		t.Errorf("expected 2 default regions, got %d", len(cfg.Regions))
	}
}

func TestLoadConfig_CustomFile(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "regions.json")
	content := `{
		"regions": [
			{"countryCode": "se", "currency": "SEK", "locale": "sv-se"},
			{"countryCode": "no", "currency": "NOK", "locale": "nb-no"},
			{"countryCode": "dk", "currency": "DKK", "locale": "da-dk"}
		]
	}`
	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
		t.Fatalf("write test file: %v", err)
	}

	cfg, err := LoadConfig(path)
	if err != nil {
		t.Fatalf("LoadConfig failed: %v", err)
	}
	if len(cfg.Regions) != 3 {
		t.Fatalf("expected 3 regions, got %d", len(cfg.Regions))
	}

	if got := cfg.CurrencyOf("dk"); got != "DKK" {
		t.Errorf("CurrencyOf(dk) = %s, want DKK", got)
	}
	if got := cfg.LocaleOf("dk"); got != "da-dk" {
		t.Errorf("LocaleOf(dk) = %s, want da-dk", got)
	}
	if got := cfg.CountryFromCurrency("DKK"); got != "dk" {
		t.Errorf("CountryFromCurrency(DKK) = %s, want dk", got)
	}
}

func TestLoadConfig_NormalisesCountryCode(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "regions.json")
	content := `{"regions": [{"countryCode": "NO", "currency": "NOK", "locale": "nb-no"}]}`
	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
		t.Fatalf("write test file: %v", err)
	}

	cfg, err := LoadConfig(path)
	if err != nil {
		t.Fatalf("LoadConfig failed: %v", err)
	}
	if got := cfg.CurrencyOf("NO"); got != "NOK" {
		t.Errorf("CurrencyOf(NO) = %s, want NOK", got)
	}
	if got := cfg.CurrencyOf("no"); got != "NOK" {
		t.Errorf("CurrencyOf(no) = %s, want NOK", got)
	}
}