package config

import (
	"fmt"
	"os"
	"time"

	"gopkg.in/yaml.v3"
)

type Config struct {
	Server      ServerConfig      `yaml:"server"`
	Vault       VaultConfig       `yaml:"vault"`
	Git         GitConfig         `yaml:"git"`
	Index       IndexConfig       `yaml:"index"`
	Search      SearchConfig      `yaml:"search"`
	Cache       CacheConfig       `yaml:"cache"`
	Logging     LoggingConfig     `yaml:"logging"`
	Performance PerformanceConfig `yaml:"performance"`
	Security    SecurityConfig    `yaml:"security"`
}

type ServerConfig struct {
	Name      string `yaml:"name"`
	Version   string `yaml:"version"`
	Transport string `yaml:"transport"` // "stdio" or "sse"
}

type VaultConfig struct {
	Path         string   `yaml:"path"`
	ExcludePaths []string `yaml:"exclude_paths"`
	WatchChanges bool     `yaml:"watch_changes"`
}

type GitConfig struct {
	Enabled      bool   `yaml:"enabled"`
	AutoPull     bool   `yaml:"auto_pull"`
	AutoPush     bool   `yaml:"auto_push"`
	AutoCommit   bool   `yaml:"auto_commit"`
	CommitPrefix string `yaml:"commit_prefix"`
	Remote       string `yaml:"remote"`
	Branch       string `yaml:"branch"`
}

type IndexConfig struct {
	BuildOnStartup    bool          `yaml:"build_on_startup"`
	RebuildInterval   time.Duration `yaml:"rebuild_interval"`
	MaxNotesInMemory  int           `yaml:"max_notes_in_memory"`
}

type SearchConfig struct {
	MaxResults     int  `yaml:"max_results"`
	ContextLines   int  `yaml:"context_lines"`
	CaseSensitive  bool `yaml:"case_sensitive"`
}

type CacheConfig struct {
	Enabled bool          `yaml:"enabled"`
	MaxSize int           `yaml:"max_size"`
	TTL     time.Duration `yaml:"ttl"`
}

type LoggingConfig struct {
	Level  string `yaml:"level"`  // debug, info, warn, error
	Format string `yaml:"format"` // text or json
	File   string `yaml:"file"`
}

type PerformanceConfig struct {
	MaxConcurrentOperations int           `yaml:"max_concurrent_operations"`
	ReadTimeout             time.Duration `yaml:"read_timeout"`
	WriteTimeout            time.Duration `yaml:"write_timeout"`
}

type RateLimitConfig struct {
	Enabled           bool `yaml:"enabled"`
	RequestsPerSecond int  `yaml:"requests_per_second"`
	Burst             int  `yaml:"burst"`
}

type SecurityConfig struct {
	RateLimit   RateLimitConfig `yaml:"rate_limit"`
	MaxFileSize string          `yaml:"max_file_size"`
}

func NewDefaultConfig() *Config {
	return &Config{
		Server: ServerConfig{
			Name:      "obsidian-mcp",
			Version:   "1.0.0",
			Transport: "stdio",
		},
		Vault: VaultConfig{
			Path: "",
			ExcludePaths: []string{
				".obsidian/",
				".git/",
				".trash/",
			},
			WatchChanges: true,
		},
		Git: GitConfig{
			Enabled:      true,
			AutoPull:     true,
			AutoPush:     false,
			AutoCommit:   true,
			CommitPrefix: "[MCP]",
			Remote:       "origin",
			Branch:       "main",
		},
		Index: IndexConfig{
			BuildOnStartup:   true,
			RebuildInterval:  5 * time.Minute,
			MaxNotesInMemory: 10000,
		},
		Search: SearchConfig{
			MaxResults:    50,
			ContextLines:  2,
			CaseSensitive: false,
		},
		Cache: CacheConfig{
			Enabled: true,
			MaxSize: 1000,
			TTL:     5 * time.Minute,
		},
		Logging: LoggingConfig{
			Level:  "info",
			Format: "text",
			File:   "",
		},
		Performance: PerformanceConfig{
			MaxConcurrentOperations: 10,
			ReadTimeout:             30 * time.Second,
			WriteTimeout:            30 * time.Second,
		},
		Security: SecurityConfig{
			RateLimit: RateLimitConfig{
				Enabled:           true,
				RequestsPerSecond: 10,
				Burst:             20,
			},
			MaxFileSize: "10MB",
		},
	}
}

func LoadConfig(path string) (*Config, error) {
	config := NewDefaultConfig()

	if path == "" {
		return config, nil
	}

	data, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return config, nil
		}
		return nil, fmt.Errorf("failed to read config file: %w", err)
	}

	if err := yaml.Unmarshal(data, config); err != nil {
		return nil, fmt.Errorf("failed to parse config file: %w", err)
	}

	if err := config.Validate(); err != nil {
		return nil, fmt.Errorf("invalid config: %w", err)
	}

	return config, nil
}

func LoadConfigFromEnv() (*Config, error) {
	config := NewDefaultConfig()

	if vaultPath := os.Getenv("VAULT_PATH"); vaultPath != "" {
		config.Vault.Path = vaultPath
	}

	if logLevel := os.Getenv("LOG_LEVEL"); logLevel != "" {
		config.Logging.Level = logLevel
	}

	if gitEnabled := os.Getenv("GIT_ENABLED"); gitEnabled == "false" {
		config.Git.Enabled = false
	}

	if gitAutoPush := os.Getenv("GIT_AUTO_PUSH"); gitAutoPush == "true" {
		config.Git.AutoPush = true
	}

	if cacheEnabled := os.Getenv("CACHE_ENABLED"); cacheEnabled == "false" {
		config.Cache.Enabled = false
	}

	return config, config.Validate()
}

func (c *Config) Validate() error {
	if c.Vault.Path == "" {
		return fmt.Errorf("vault path is required")
	}

	if c.Server.Transport != "stdio" && c.Server.Transport != "sse" {
		return fmt.Errorf("invalid transport: %s", c.Server.Transport)
	}

	if c.Search.MaxResults <= 0 {
		return fmt.Errorf("max results must be positive")
	}

	if c.Cache.MaxSize <= 0 {
		return fmt.Errorf("cache max size must be positive")
	}

	validLogLevels := map[string]bool{
		"debug": true,
		"info":  true,
		"warn":  true,
		"error": true,
	}

	if !validLogLevels[c.Logging.Level] {
		return fmt.Errorf("invalid log level: %s", c.Logging.Level)
	}

	return nil
}

func (c *Config) SaveToFile(path string) error {
	data, err := yaml.Marshal(c)
	if err != nil {
		return fmt.Errorf("failed to marshal config: %w", err)
	}

	if err := os.WriteFile(path, data, 0644); err != nil {
		return fmt.Errorf("failed to write config file: %w", err)
	}

	return nil
}