package config

import (
	"log/slog"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/spf13/viper"
)

// initDir makes a temp working directory holding a .env file (if env is not
// nil) and a config.yaml (if config is not empty), and returns its path.
func initDir(t *testing.T, env []string, config string) string {
	t.Helper()
	resetViper(t)
	dir := t.TempDir()
	t.Chdir(dir)
	if env != nil {
		// godotenv sets variables without cleaning up after the test.
		for _, kv := range env {
			key, _, _ := strings.Cut(kv, "=")
			t.Cleanup(func() { os.Unsetenv(key) })
		}
		writeFile(t, filepath.Join(dir, ".env"), strings.Join(env, "\n")+"\n")
	}
	if config != "" {
		writeFile(t, filepath.Join(dir, "config.yaml"), config)
	}
	return dir
}

func writeFile(t *testing.T, path, contents string) {
	t.Helper()
	if err := os.WriteFile(path, []byte(contents), 0o600); err != nil {
		t.Fatal(err)
	}
}

const testConfigYAML = `logging:
  level: info
sources:
  fts_mock:
    enabled: true
    interval: 30s
`

func TestInitLoadsEnvAndConfigFile(t *testing.T) {
	initDir(t, []string{"JOBSEARCH_TEST_ENV=from-dotenv"}, testConfigYAML)
	captureLogs(t, slog.LevelError)

	var conf JobSearchConfig
	if err := Init("", &conf); err != nil {
		t.Fatal(err)
	}
	if got := os.Getenv("JOBSEARCH_TEST_ENV"); got != "from-dotenv" {
		t.Errorf("JOBSEARCH_TEST_ENV = %q; want it loaded from .env", got)
	}
	if conf.Logging.Level != "info" {
		t.Errorf("Logging.Level = %q; want info", conf.Logging.Level)
	}
	if !conf.Sources.FTSMock.Enabled || conf.Sources.FTSMock.Interval != 30*time.Second {
		t.Errorf("FTSMock = %+v; want enabled every 30s", conf.Sources.FTSMock)
	}
	// Keys missing from the file keep their defaults.
	if conf.Sources.FindATender.Interval != 10*time.Minute {
		t.Errorf("FindATender.Interval = %v; want default 10m", conf.Sources.FindATender.Interval)
	}
}

func TestInitExplicitConfigFile(t *testing.T) {
	dir := initDir(t, []string{}, "logging:\n  level: info\n")
	other := filepath.Join(dir, "other.yaml")
	writeFile(t, other, "logging:\n  level: error\n")
	captureLogs(t, slog.LevelError)

	var conf JobSearchConfig
	if err := Init(other, &conf); err != nil {
		t.Fatal(err)
	}
	if conf.Logging.Level != "error" {
		t.Errorf("Logging.Level = %q; want error from %s", conf.Logging.Level, other)
	}
}

func TestInitNoConfigFile(t *testing.T) {
	initDir(t, []string{}, "")
	logs := captureLogs(t, slog.LevelWarn)

	var conf JobSearchConfig
	if err := Init("", &conf); err != nil {
		t.Fatal(err)
	}
	if !strings.Contains(logs.String(), "No config file found") {
		t.Errorf("no warning logged: %s", logs)
	}
	if conf.Logging.Level != "warn" {
		t.Errorf("Logging.Level = %q; want default warn", conf.Logging.Level)
	}
}

// The -debug and -quiet levels set before Init win over the config file.
func TestInitKeepsCommandLineLevel(t *testing.T) {
	for _, level := range []string{"debug", "error"} {
		t.Run(level, func(t *testing.T) {
			initDir(t, []string{}, "logging:\n  level: info\n")
			logs := captureLogs(t, slog.LevelDebug)

			conf := JobSearchConfig{Logging: JSCLogging{Level: level}}
			if err := Init("", &conf); err != nil {
				t.Fatal(err)
			}
			if conf.Logging.Level != level {
				t.Errorf("Logging.Level = %q; want %s kept", conf.Logging.Level, level)
			}
			// At debug, the environment and loaded config are logged.
			gotDebug := strings.Contains(logs.String(), "Loaded config:")
			if gotDebug != (level == "debug") {
				t.Errorf("debug output logged = %v at level %s: %s", gotDebug, level, logs)
			}
		})
	}
}

func TestInitErrors(t *testing.T) {
	t.Run("no .env file", func(t *testing.T) {
		initDir(t, nil, testConfigYAML)
		var conf JobSearchConfig
		if err := Init("", &conf); err == nil || !strings.Contains(err.Error(), ".env") {
			t.Fatalf("err = %v; want an invalid .env file error", err)
		}
	})
	t.Run("invalid config file", func(t *testing.T) {
		initDir(t, []string{}, "logging: [unclosed\n")
		captureLogs(t, slog.LevelError)
		var conf JobSearchConfig
		if err := Init("", &conf); err == nil {
			t.Fatal("expected an error for invalid YAML")
		}
	})
	t.Run("missing explicit config file", func(t *testing.T) {
		dir := initDir(t, []string{}, "")
		captureLogs(t, slog.LevelError)
		var conf JobSearchConfig
		if err := Init(filepath.Join(dir, "missing.yaml"), &conf); err == nil {
			t.Fatal("expected an error for a missing config file")
		}
	})
}

// Environment variables override the config file, with nested keys joined
// by underscores.
func TestInitEnvOverride(t *testing.T) {
	initDir(t, []string{}, testConfigYAML)
	captureLogs(t, slog.LevelError)
	t.Setenv("JOBSEARCH_LOGGING_LEVEL", "error")
	t.Setenv("JOBSEARCH_SOURCES_FTS_MOCK_INTERVAL", "45s")

	var conf JobSearchConfig
	if err := Init("", &conf); err != nil {
		t.Fatal(err)
	}
	if conf.Logging.Level != "error" {
		t.Errorf("Logging.Level = %q; want error from the environment", conf.Logging.Level)
	}
	if conf.Sources.FTSMock.Interval != 45*time.Second {
		t.Errorf("FTSMock.Interval = %v; want 45s from the environment", conf.Sources.FTSMock.Interval)
	}
}

func TestEnvVarName(t *testing.T) {
	tests := map[string]string{
		"logging.level":                             "JOBSEARCH_LOGGING_LEVEL",
		"sources.fts_mock.interval":                 "JOBSEARCH_SOURCES_FTS_MOCK_INTERVAL",
		"server.websocket.connection_limit.enabled": "JOBSEARCH_SERVER_WEBSOCKET_CONNECTION_LIMIT_ENABLED",
	}
	for key, want := range tests {
		if got := envVarName(key); got != want {
			t.Errorf("envVarName(%q) = %q; want %q", key, got, want)
		}
	}
}

// explicitConfigYAML sets a top-level and a nested key in a config file.
const explicitConfigYAML = `logging:
  level: info
server:
  websocket:
    connection_limit:
      enabled: true
`

// loadExplicit sets up Viper as Init does, with the defaults, the config
// file explicitConfigYAML and the JOBSEARCH_* environment variables.
func loadExplicit(t *testing.T) {
	t.Helper()
	resetViper(t)
	LoadDefaultConfig()
	viper.SetEnvPrefix(EnvPrefix)
	viper.SetEnvKeyReplacer(envKeyReplacer)
	viper.AutomaticEnv()
	viper.SetConfigType("yaml")
	if err := viper.ReadConfig(strings.NewReader(explicitConfigYAML)); err != nil {
		t.Fatal(err)
	}
}

// A key is explicitly set by the config file or a non-empty environment
// variable, not by its default or viper.Set.
func TestIsExplicitlySet(t *testing.T) {
	t.Setenv("JOBSEARCH_DATABASE_FILE", "/tmp/js.db")
	t.Setenv("JOBSEARCH_LOGGING_FILE", "")
	loadExplicit(t)
	viper.Set("sources.sleeper.enabled", true)

	tests := map[string]bool{
		"logging.level": true, // config file
		"server.websocket.connection_limit.enabled": true, // nested, config file
		"database.file":                           true,  // environment
		"logging.file":                            false, // empty environment variable
		"sources.sleeper.interval":                false, // default only
		"sources.sleeper.enabled":                 false, // viper.Set
		"server.websocket.connection_limit.burst": false, // default, beside a set key
	}
	for key, want := range tests {
		if got := isExplicitlySet(key); got != want {
			t.Errorf("isExplicitlySet(%q) = %v; want %v", key, got, want)
		}
	}
}

// printLoadedConfig logs only the keys set by the config file or the
// environment.
func TestPrintLoadedConfig(t *testing.T) {
	t.Setenv("JOBSEARCH_DATABASE_FILE", "/tmp/js.db")
	loadExplicit(t)
	logs := captureLogs(t, slog.LevelDebug)
	printLoadedConfig()

	out := logs.String()
	for _, want := range []string{
		`logging.level = \"info\" <string>`,
		`server.websocket.connection_limit.enabled = true <bool>`,
		`database.file = \"/tmp/js.db\" <string>`,
	} {
		if !strings.Contains(out, want) {
			t.Errorf("missing %q in:\n%s", want, out)
		}
	}
	for _, unwanted := range []string{"sources.", "logging.file", "connection_limit.burst"} {
		if strings.Contains(out, unwanted) {
			t.Errorf("logged default key %q:\n%s", unwanted, out)
		}
	}
}