package config

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

func TestLoadDotEnvFileParsesAndPreservesExistingValues(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, ".env")
	content := "" +
		"# comment\n" +
		"KEY1 = value1\n" +
		"KEY2='quoted value'\n" +
		"KEY3=\"double quoted\"\n" +
		"INVALID_LINE\n" +
		"=missing_key\n"

	if err := os.WriteFile(path, []byte(content), 0o600); err != nil {
		t.Fatalf("write env file: %v", err)
	}

	t.Setenv("KEY1", "existing")
	_ = os.Unsetenv("KEY2")
	_ = os.Unsetenv("KEY3")

	if ok := loadDotEnvFile(path); !ok {
		t.Fatal("expected loadDotEnvFile to return true")
	}

	if got := os.Getenv("KEY1"); got != "existing" {
		t.Fatalf("expected KEY1 to preserve existing value, got %q", got)
	}
	if got := os.Getenv("KEY2"); got != "quoted value" {
		t.Fatalf("expected KEY2 parsed value, got %q", got)
	}
	if got := os.Getenv("KEY3"); got != "double quoted" {
		t.Fatalf("expected KEY3 parsed value, got %q", got)
	}
}

func TestLoadDotEnvCandidatesStopsAtFirstExistingFile(t *testing.T) {
	dir := t.TempDir()
	first := filepath.Join(dir, "first.env")
	second := filepath.Join(dir, "second.env")

	if err := os.WriteFile(first, []byte("KEY_A=first\nKEY_B=from_first\n"), 0o600); err != nil {
		t.Fatalf("write first env file: %v", err)
	}
	if err := os.WriteFile(second, []byte("KEY_A=second\nKEY_C=from_second\n"), 0o600); err != nil {
		t.Fatalf("write second env file: %v", err)
	}

	_ = os.Unsetenv("KEY_A")
	_ = os.Unsetenv("KEY_B")
	_ = os.Unsetenv("KEY_C")

	LoadDotEnvCandidates([]string{filepath.Join(dir, "missing.env"), first, second})

	if got := os.Getenv("KEY_A"); got != "first" {
		t.Fatalf("expected KEY_A from first file, got %q", got)
	}
	if got := os.Getenv("KEY_B"); got != "from_first" {
		t.Fatalf("expected KEY_B from first file, got %q", got)
	}
	if got := os.Getenv("KEY_C"); got != "" {
		t.Fatalf("expected KEY_C to remain unset, got %q", got)
	}
}

func TestLoadDotEnvFileReturnsFalseWhenMissing(t *testing.T) {
	if ok := loadDotEnvFile(filepath.Join(t.TempDir(), "does-not-exist.env")); ok {
		t.Fatal("expected loadDotEnvFile to return false for missing file")
	}
}