package config

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"testing"
)

func noSystemConfig(t *testing.T) {
	t.Helper()
	old := systemConfigPath
	systemConfigPath = filepath.Join(t.TempDir(), "absent.conf")
	t.Cleanup(func() { systemConfigPath = old })
}

func setConfKey(t *testing.T, key, value string) string {
	t.Helper()
	path := filepath.Join(t.TempDir(), "openstore.conf")
	buff, err := os.ReadFile("testdata/full.conf")
	if err != nil {
		t.Fatalf("read full.conf: %v", err)
	}

	expr := fmt.Sprintf("(%s)\\s*=.*", key)
	repl := fmt.Sprintf("${1} = %s", value)

	re := regexp.MustCompile(expr)
	result := re.ReplaceAll(buff, []byte(repl))

	if err = os.WriteFile(path, result, 0o644); err != nil {
		t.Fatalf("write conf: %v", err)
	}

	return path
}

func TestRejectLoadingMissingFile(t *testing.T) {
	noSystemConfig(t)

	_, err := Load(filepath.Join(t.TempDir(), "nonexistent.conf"))
	if err == nil {
		t.Fatalf("no error when loading missing config: %v", err)
	}
}

func TestLoadFullConfig(t *testing.T) {
	noSystemConfig(t)

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

	tests := []struct {
		field string
		got   string
		want  string
	}{
		{"addr", cfg.Serve.Addr, "127.0.0.1:8080"},
		{"name", cfg.Instance.Name, "Full Store"},
		{"contact-email", cfg.Instance.ContactEmail, "full@store.com"},
		{"base-url", cfg.Instance.BaseURL, "https://full.store.com"},
		{"database-name", cfg.Database.Name, "openstore"},
		{"database-user", cfg.Database.User, "openstore"},
		{"database-password", cfg.Database.Password, "12345678"},
	}

	for _, tt := range tests {
		if tt.got != tt.want {
			t.Errorf("%s: got %q, want %q", tt.field, tt.got, tt.want)
		}
	}
}

func TestLoadUserConfigWinsOverSystem(t *testing.T) {
	old := systemConfigPath
	systemConfigPath = "testdata/system.conf"
	t.Cleanup(func() { systemConfigPath = old })

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

	if cfg.Instance.Name != "Only Name Set" {
		t.Errorf("user config should win, got name %q", cfg.Instance.Name)
	}
	if cfg.Instance.ContactEmail != "system@store.com" {
		t.Errorf("key absent from user config should fall back to system, got %q",
			cfg.Instance.ContactEmail)
	}
	if cfg.Serve.Addr != "127.0.0.1:9999" {
		t.Errorf("section absent from user config should fall back to system, got %q",
			cfg.Serve.Addr)
	}
}

func TestLoadMalformedFile(t *testing.T) {
	noSystemConfig(t)

	if _, err := Load("testdata/malformed.conf"); err == nil {
		t.Error("malformed config file loaded without error")
	}
}

func TestLoadRejectsBadBaseURL(t *testing.T) {
	noSystemConfig(t)

	tests := map[string]string{
		"not a url":      "garbage",
		"no scheme":      "example.com/path",
		"scheme only":    "https://",
		"path only":      "/listings",
		"bad url syntax": "://x",
	}

	for name, badURL := range tests {
		t.Run(name, func(t *testing.T) {
			path := setConfKey(t, "base-url", badURL)

			cfg, err := Load(path)
			if cfg != nil {
				t.Error("config with bad base-url created")
			}

			if !errors.Is(err, ErrBadConfigUrl) {
				t.Fatalf("bad base-url %q accepted", badURL)
			}

			if !strings.Contains(err.Error(), "base-url") {
				t.Errorf("error should mention base-url, got: %v", err)
			}
		})
	}
}

func TestLoadAcceptsGoodBaseURL(t *testing.T) {
	noSystemConfig(t)

	urls := []string{
		"https://example.com",
		"http://example.com",
		"https://example.com/subpath",
		"https://sub.example.com:8443",
	}

	for _, u := range urls {
		t.Run(u, func(t *testing.T) {
			path := setConfKey(t, "base-url", u)

			cfg, err := Load(path)
			if err != nil {
				t.Fatalf("good url %q rejected: %v", u, err)
			}
			if cfg.Instance.BaseURL != u {
				t.Errorf("base-url: got %q, want %q", cfg.Instance.BaseURL, u)
			}
		})
	}
}

func TetsRejectsConfigWithoutDatabase(t *testing.T) {
	noSystemConfig(t)
	_, err := Load("testdata/no-db.conf")
	if err == nil {
		t.Errorf("Load returned no error when database config is missing")
	}

	if !errors.Is(err, ErrBadConfig) {
		t.Errorf("Got error %v, wanted %v", err, ErrBadConfig)
	}
}

func TestDefaultPath(t *testing.T) {
	t.Setenv("XDG_CONFIG_HOME", "/tmp/xdg-test")

	path, err := DefaultPath()
	if err != nil {
		t.Fatalf("DefaultPath: %v", err)
	}

	want := filepath.Join("/tmp/xdg-test", "openstore", "openstore.conf")
	if path != want {
		t.Errorf("got %q, want %q", path, want)
	}
}

func TestDefaultPathWithoutConfigDir(t *testing.T) {
	t.Setenv("XDG_CONFIG_HOME", "")
	t.Setenv("HOME", "")

	if _, err := DefaultPath(); err == nil {
		t.Error("DefaultPath returned no error with no config dir available")
	}
}