package config

import (
	"context"
	"os"
	"path/filepath"
	"testing"
	"time"

	"github.com/break/junhong_cmp_fiber/pkg/constants"
	"github.com/spf13/viper"
	"go.uber.org/zap"
	"go.uber.org/zap/zaptest"
)

// TestWatch tests the config hot reload watcher
func TestWatch(t *testing.T) {
	// Reset viper
	viper.Reset()

	// Create temp config file
	tmpDir := t.TempDir()
	configFile := filepath.Join(tmpDir, "config.yaml")

	// Initial config
	initialContent := `
server:
  address: ":3000"
  read_timeout: "10s"
  write_timeout: "10s"
  shutdown_timeout: "30s"
  prefork: false

redis:
  address: "localhost"
  port: 6379
  password: ""
  db: 0
  pool_size: 10
  min_idle_conns: 5
  dial_timeout: "5s"
  read_timeout: "3s"
  write_timeout: "3s"

logging:
  level: "info"
  development: false
  app_log:
    filename: "logs/app.log"
    max_size: 100
    max_backups: 30
    max_age: 30
    compress: true
  access_log:
    filename: "logs/access.log"
    max_size: 500
    max_backups: 90
    max_age: 90
    compress: true

middleware:
  enable_auth: true
  enable_rate_limiter: false
  rate_limiter:
    max: 100
    expiration: "1m"
    storage: "memory"
`
	if err := os.WriteFile(configFile, []byte(initialContent), 0644); err != nil {
		t.Fatalf("failed to create config file: %v", err)
	}

	// Set config path
	os.Setenv(constants.EnvConfigPath, configFile)
	defer os.Unsetenv(constants.EnvConfigPath)

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

	// Verify initial values
	if cfg.Logging.Level != "info" {
		t.Fatalf("expected initial logging.level info, got %s", cfg.Logging.Level)
	}

	// Create logger for testing
	logger := zaptest.NewLogger(t)

	// Start watcher in goroutine with context
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	go Watch(ctx, logger)

	// Give watcher time to initialize
	time.Sleep(100 * time.Millisecond)

	// Modify config file to trigger hot reload
	updatedContent := `
server:
  address: ":8080"
  read_timeout: "15s"
  write_timeout: "15s"
  shutdown_timeout: "30s"
  prefork: false

redis:
  address: "localhost"
  port: 6379
  password: ""
  db: 0
  pool_size: 20
  min_idle_conns: 10
  dial_timeout: "5s"
  read_timeout: "3s"
  write_timeout: "3s"

logging:
  level: "debug"
  development: true
  app_log:
    filename: "logs/app.log"
    max_size: 100
    max_backups: 30
    max_age: 30
    compress: true
  access_log:
    filename: "logs/access.log"
    max_size: 500
    max_backups: 90
    max_age: 90
    compress: true

middleware:
  enable_auth: false
  enable_rate_limiter: true
  rate_limiter:
    max: 200
    expiration: "2m"
    storage: "redis"
`
	if err := os.WriteFile(configFile, []byte(updatedContent), 0644); err != nil {
		t.Fatalf("failed to update config file: %v", err)
	}

	// Wait for watcher to detect and process changes (spec requires detection within 5 seconds)
	// We use a more aggressive timeout for testing
	time.Sleep(2 * time.Second)

	// Verify config was reloaded
	reloadedCfg := Get()
	if reloadedCfg.Logging.Level != "debug" {
		t.Errorf("expected config hot reload, got logging.level %s instead of debug", reloadedCfg.Logging.Level)
	}
	if reloadedCfg.Server.Address != ":8080" {
		t.Errorf("expected config hot reload, got server.address %s instead of :8080", reloadedCfg.Server.Address)
	}
	if reloadedCfg.Redis.PoolSize != 20 {
		t.Errorf("expected config hot reload, got redis.pool_size %d instead of 20", reloadedCfg.Redis.PoolSize)
	}

	// Cancel context to stop watcher
	cancel()

	// Give watcher time to shut down gracefully
	time.Sleep(100 * time.Millisecond)
}

// TestWatch_InvalidConfigRejected tests that invalid config changes are rejected
func TestWatch_InvalidConfigRejected(t *testing.T) {
	// Reset viper
	viper.Reset()

	// Create temp config file
	tmpDir := t.TempDir()
	configFile := filepath.Join(tmpDir, "config.yaml")

	// Initial valid config
	validContent := `
server:
  address: ":3000"
  read_timeout: "10s"
  write_timeout: "10s"
  shutdown_timeout: "30s"
  prefork: false

redis:
  address: "localhost"
  port: 6379
  password: ""
  db: 0
  pool_size: 10
  min_idle_conns: 5
  dial_timeout: "5s"
  read_timeout: "3s"
  write_timeout: "3s"

logging:
  level: "info"
  development: false
  app_log:
    filename: "logs/app.log"
    max_size: 100
    max_backups: 30
    max_age: 30
    compress: true
  access_log:
    filename: "logs/access.log"
    max_size: 500
    max_backups: 90
    max_age: 90
    compress: true

middleware:
  enable_auth: true
  enable_rate_limiter: false
  rate_limiter:
    max: 100
    expiration: "1m"
    storage: "memory"
`
	if err := os.WriteFile(configFile, []byte(validContent), 0644); err != nil {
		t.Fatalf("failed to create config file: %v", err)
	}

	// Set config path
	os.Setenv(constants.EnvConfigPath, configFile)
	defer os.Unsetenv(constants.EnvConfigPath)

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

	initialLevel := cfg.Logging.Level
	if initialLevel != "info" {
		t.Fatalf("expected initial logging.level info, got %s", initialLevel)
	}

	// Create logger for testing
	logger := zaptest.NewLogger(t)

	// Start watcher
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	go Watch(ctx, logger)

	// Give watcher time to initialize
	time.Sleep(100 * time.Millisecond)

	// Write INVALID config (malformed YAML)
	invalidContent := `
server:
  address: ":3000"
  invalid yaml syntax here!!!
`
	if err := os.WriteFile(configFile, []byte(invalidContent), 0644); err != nil {
		t.Fatalf("failed to write invalid config: %v", err)
	}

	// Wait for watcher to detect changes
	time.Sleep(2 * time.Second)

	// Verify config was NOT changed (should keep previous valid config)
	currentCfg := Get()
	if currentCfg.Logging.Level != initialLevel {
		t.Errorf("expected config to remain unchanged after invalid update, got logging.level %s instead of %s", currentCfg.Logging.Level, initialLevel)
	}

	// Restore valid config
	if err := os.WriteFile(configFile, []byte(validContent), 0644); err != nil {
		t.Fatalf("failed to restore valid config: %v", err)
	}

	time.Sleep(500 * time.Millisecond)

	// Now write config with validation error (timeout out of range)
	invalidValidationContent := `
server:
  address: ":3000"
  read_timeout: "1s"
  write_timeout: "10s"
  shutdown_timeout: "30s"

redis:
  address: "localhost"
  port: 6379
  db: 0
  pool_size: 10
  min_idle_conns: 5

logging:
  level: "debug"
  app_log:
    filename: "logs/app.log"
    max_size: 100
    max_backups: 30
    max_age: 30
    compress: true
  access_log:
    filename: "logs/access.log"
    max_size: 500
    max_backups: 90
    max_age: 90
    compress: true

middleware:
  enable_auth: true
  rate_limiter:
    max: 100
    expiration: "1m"
    storage: "memory"
`
	if err := os.WriteFile(configFile, []byte(invalidValidationContent), 0644); err != nil {
		t.Fatalf("failed to write config with validation error: %v", err)
	}

	// Wait for watcher to detect changes
	time.Sleep(2 * time.Second)

	// Verify config was NOT changed (validation should have failed)
	finalCfg := Get()
	if finalCfg.Logging.Level != initialLevel {
		t.Errorf("expected config to remain unchanged after validation error, got logging.level %s instead of %s", finalCfg.Logging.Level, initialLevel)
	}
	if finalCfg.Server.ReadTimeout == 1*time.Second {
		t.Error("expected config to remain unchanged, but read_timeout was updated to invalid value")
	}

	// Cancel context
	cancel()
	time.Sleep(100 * time.Millisecond)
}

// TestWatch_ContextCancellation tests graceful shutdown on context cancellation
func TestWatch_ContextCancellation(t *testing.T) {
	// Reset viper
	viper.Reset()

	// Create temp config file
	tmpDir := t.TempDir()
	configFile := filepath.Join(tmpDir, "config.yaml")

	content := `
server:
  address: ":3000"
  read_timeout: "10s"
  write_timeout: "10s"
  shutdown_timeout: "30s"

redis:
  address: "localhost"
  port: 6379
  db: 0
  pool_size: 10
  min_idle_conns: 5

logging:
  level: "info"
  app_log:
    filename: "logs/app.log"
    max_size: 100
    max_backups: 30
    max_age: 30
    compress: true
  access_log:
    filename: "logs/access.log"
    max_size: 500
    max_backups: 90
    max_age: 90
    compress: true

middleware:
  enable_auth: true
  rate_limiter:
    max: 100
    expiration: "1m"
    storage: "memory"
`
	if err := os.WriteFile(configFile, []byte(content), 0644); err != nil {
		t.Fatalf("failed to create config file: %v", err)
	}

	os.Setenv(constants.EnvConfigPath, configFile)
	defer os.Unsetenv(constants.EnvConfigPath)

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

	// Create logger
	logger := zap.NewNop() // Use no-op logger for this test

	// Start watcher with context
	ctx, cancel := context.WithCancel(context.Background())

	done := make(chan bool)
	go func() {
		Watch(ctx, logger)
		done <- true
	}()

	// Give watcher time to start
	time.Sleep(100 * time.Millisecond)

	// Cancel context (simulate graceful shutdown)
	cancel()

	// Wait for watcher to stop (should happen quickly)
	select {
	case <-done:
		// Watcher stopped successfully
	case <-time.After(2 * time.Second):
		t.Error("watcher did not stop within timeout after context cancellation")
	}
}