package config_test

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

	"github.com/jackc/pgx/v5/pgxpool"

	"github.com/travelswitch/travelhub/backend/internal/config"
)

// isolate points the process at an empty directory and clears every variable
// Load reads, so one test cannot inherit another's environment -- or the
// developer's real .env.
func isolate(t *testing.T) {
	t.Helper()

	for _, key := range []string{
		"DATABASE_URL", "DB_HOST", "DB_PORT", "DB_USER", "DB_PASSWORD",
		"DB_NAME", "DB_SSLMODE", "PORT", "CORS_ORIGINS",
	} {
		t.Setenv(key, "")
		os.Unsetenv(key)
	}
	t.Chdir(t.TempDir())
}

func TestLoadDefaults(t *testing.T) {
	isolate(t)
	t.Setenv("DB_PASSWORD", "secret")

	cfg, err := config.Load()
	if err != nil {
		t.Fatalf("load: %v", err)
	}

	if cfg.Port != "8080" {
		t.Errorf("Port = %q, want 8080", cfg.Port)
	}
	if len(cfg.CORSOrigins) != 1 || cfg.CORSOrigins[0] != "http://localhost:4200" {
		t.Errorf("CORSOrigins = %v, want the Angular dev server", cfg.CORSOrigins)
	}
	if !strings.Contains(cfg.DatabaseURL, "/travelhub") {
		t.Errorf("DatabaseURL = %q, want the default database name", cfg.DatabaseURL)
	}
}

func TestLoadRequiresAPassword(t *testing.T) {
	isolate(t)

	_, err := config.Load()
	if err == nil {
		t.Fatal("want an error when neither DATABASE_URL nor DB_PASSWORD is set")
	}
	if !strings.Contains(err.Error(), "DB_PASSWORD") {
		t.Errorf("error should name the missing variable, got: %v", err)
	}
}

// The credentials in use here contain '@', which is exactly the character that
// breaks naive string concatenation into a DSN.
func TestLoadEscapesAwkwardPasswords(t *testing.T) {
	isolate(t)

	awkward := []string{
		// Synthetic values only — never a real, in-use password (see the VAPT
		// report, FINDING-8). Each still exercises a reserved DSN character.
		"S3cr3t@x",
		"p@ss:word/with?reserved#chars",
		"has spaces and %25 percent",
		"trailing@@@",
	}

	for _, password := range awkward {
		t.Run(password, func(t *testing.T) {
			t.Setenv("DB_PASSWORD", password)
			t.Setenv("DB_USER", "postgres")
			t.Setenv("DB_NAME", "travelhub")

			cfg, err := config.Load()
			if err != nil {
				t.Fatalf("load: %v", err)
			}

			// The real proof is that the driver can parse it back out.
			parsed, err := pgxpool.ParseConfig(cfg.DatabaseURL)
			if err != nil {
				t.Fatalf("pgx could not parse %q: %v", cfg.DatabaseURL, err)
			}
			if parsed.ConnConfig.Password != password {
				t.Errorf("round-tripped password = %q, want %q",
					parsed.ConnConfig.Password, password)
			}
			if parsed.ConnConfig.Database != "travelhub" {
				t.Errorf("database = %q, want travelhub", parsed.ConnConfig.Database)
			}
		})
	}
}

func TestDatabaseURLWinsOverParts(t *testing.T) {
	isolate(t)
	const explicit = "postgres://someone:else@db.internal:6543/other?sslmode=require"

	t.Setenv("DATABASE_URL", explicit)
	t.Setenv("DB_PASSWORD", "ignored")
	t.Setenv("DB_NAME", "ignored")

	cfg, err := config.Load()
	if err != nil {
		t.Fatalf("load: %v", err)
	}
	if cfg.DatabaseURL != explicit {
		t.Errorf("DatabaseURL = %q, want the explicit value", cfg.DatabaseURL)
	}
}

func TestLoadReadsDotEnv(t *testing.T) {
	isolate(t)

	dir := t.TempDir()
	contents := strings.Join([]string{
		"# a comment",
		"",
		"DB_PASSWORD=from-file",
		"DB_NAME=from-file-db",
		`DB_USER="quoted-user"`,
		"PORT=9999",
		"CORS_ORIGINS=http://a.test, http://b.test ,",
		"MALFORMED-LINE-WITHOUT-EQUALS",
	}, "\n")

	if err := os.WriteFile(filepath.Join(dir, ".env"), []byte(contents), 0o600); err != nil {
		t.Fatalf("write .env: %v", err)
	}
	t.Chdir(dir)

	cfg, err := config.Load()
	if err != nil {
		t.Fatalf("load: %v", err)
	}

	if cfg.Port != "9999" {
		t.Errorf("Port = %q, want 9999 from .env", cfg.Port)
	}
	if got := cfg.CORSOrigins; len(got) != 2 || got[0] != "http://a.test" || got[1] != "http://b.test" {
		t.Errorf("CORSOrigins = %v, want two trimmed origins", got)
	}

	parsed, err := pgxpool.ParseConfig(cfg.DatabaseURL)
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if parsed.ConnConfig.Password != "from-file" {
		t.Errorf("password = %q, want from-file", parsed.ConnConfig.Password)
	}
	if parsed.ConnConfig.Database != "from-file-db" {
		t.Errorf("database = %q, want from-file-db", parsed.ConnConfig.Database)
	}
	// Surrounding quotes are stripped rather than taken literally.
	if parsed.ConnConfig.User != "quoted-user" {
		t.Errorf("user = %q, want quoted-user", parsed.ConnConfig.User)
	}
}

// Real environment variables must beat .env, so container and CI overrides work.
func TestEnvironmentBeatsDotEnv(t *testing.T) {
	isolate(t)

	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, ".env"),
		[]byte("DB_PASSWORD=from-file\nPORT=1111\n"), 0o600); err != nil {
		t.Fatalf("write .env: %v", err)
	}
	t.Chdir(dir)
	t.Setenv("PORT", "2222")
	t.Setenv("DB_PASSWORD", "from-environment")

	cfg, err := config.Load()
	if err != nil {
		t.Fatalf("load: %v", err)
	}
	if cfg.Port != "2222" {
		t.Errorf("Port = %q, want the environment value 2222", cfg.Port)
	}

	parsed, _ := pgxpool.ParseConfig(cfg.DatabaseURL)
	if parsed.ConnConfig.Password != "from-environment" {
		t.Errorf("password = %q, want from-environment", parsed.ConnConfig.Password)
	}
}

func TestLoadFindsDotEnvInAParentDirectory(t *testing.T) {
	isolate(t)

	root := t.TempDir()
	if err := os.WriteFile(filepath.Join(root, ".env"),
		[]byte("DB_PASSWORD=parent-secret\n"), 0o600); err != nil {
		t.Fatalf("write .env: %v", err)
	}
	nested := filepath.Join(root, "cmd", "api")
	if err := os.MkdirAll(nested, 0o755); err != nil {
		t.Fatalf("mkdir: %v", err)
	}
	t.Chdir(nested)

	cfg, err := config.Load()
	if err != nil {
		t.Fatalf("load: %v", err)
	}
	parsed, _ := pgxpool.ParseConfig(cfg.DatabaseURL)
	if parsed.ConnConfig.Password != "parent-secret" {
		t.Errorf("password = %q, want parent-secret", parsed.ConnConfig.Password)
	}
}