package config

import (
	"fmt"
	"os"
	"strconv"
)

// Config holds all application configuration
type Config struct {
	// API Keys
	TodoistAPIKey     string
	PlanToEatAPIKey   string
	PlanToEatSession  string // Session cookie for web scraping
	TrelloAPIKey      string
	TrelloToken       string

	// Google Calendar
	GoogleCredentialsFile string
	GoogleCalendarID      string

	// Google Tasks
	GoogleTasksListID string

	// Paths
	DatabasePath string
	MigrationDir string
	TemplateDir  string
	StaticDir    string

	// Server
	Port            string
	CacheTTLMinutes int
	Debug           bool

	// Display
	Timezone string // IANA timezone name (e.g., "Pacific/Honolulu")
}

// Load reads configuration from environment variables
func Load() (*Config, error) {
	cfg := &Config{
		// API Keys
		TodoistAPIKey:    os.Getenv("TODOIST_API_KEY"),
		PlanToEatAPIKey:  os.Getenv("PLANTOEAT_API_KEY"),
		PlanToEatSession: os.Getenv("PLANTOEAT_SESSION"),
		TrelloAPIKey:     os.Getenv("TRELLO_API_KEY"),
		TrelloToken:      os.Getenv("TRELLO_TOKEN"),

		// Google Calendar
		GoogleCredentialsFile: os.Getenv("GOOGLE_CREDENTIALS_FILE"),
		GoogleCalendarID:      getEnvWithDefault("GOOGLE_CALENDAR_ID", "primary"),

		// Google Tasks
		GoogleTasksListID: getEnvWithDefault("GOOGLE_TASKS_LIST_ID", "@default"),

		// Paths
		DatabasePath: getEnvWithDefault("DATABASE_PATH", "./dashboard.db"),
		MigrationDir: getEnvWithDefault("MIGRATION_DIR", "migrations"),
		TemplateDir:  getEnvWithDefault("TEMPLATE_DIR", "web/templates"),
		StaticDir:    getEnvWithDefault("STATIC_DIR", "web/static"),

		// Server
		Port:            getEnvWithDefault("PORT", "8080"),
		CacheTTLMinutes: getEnvAsInt("CACHE_TTL_MINUTES", 5),
		Debug:           getEnvAsBool("DEBUG", false),

		// Display
		Timezone: getEnvWithDefault("TIMEZONE", "Pacific/Honolulu"),
	}

	// Validate required fields
	if err := cfg.Validate(); err != nil {
		return nil, err
	}

	return cfg, nil
}

// Validate checks that required configuration is present
func (c *Config) Validate() error {
	// Require both Todoist and Trello (primary task management systems)
	if c.TodoistAPIKey == "" {
		return fmt.Errorf("TODOIST_API_KEY is required")
	}

	if c.TrelloAPIKey == "" {
		return fmt.Errorf("TRELLO_API_KEY is required")
	}

	if c.TrelloToken == "" {
		return fmt.Errorf("TRELLO_TOKEN is required")
	}

	return nil
}

// HasPlanToEat checks if PlanToEat is configured (API key or session)
func (c *Config) HasPlanToEat() bool {
	return c.PlanToEatAPIKey != "" || c.PlanToEatSession != ""
}

// HasPlanToEatSession checks if PlanToEat session cookie is configured
func (c *Config) HasPlanToEatSession() bool {
	return c.PlanToEatSession != ""
}

// HasTrello checks if Trello is configured
func (c *Config) HasTrello() bool {
	return c.TrelloAPIKey != "" && c.TrelloToken != ""
}

// HasGoogleCalendar checks if Google Calendar is configured
func (c *Config) HasGoogleCalendar() bool {
	return c.GoogleCredentialsFile != ""
}

// HasGoogleTasks checks if Google Tasks is configured
func (c *Config) HasGoogleTasks() bool {
	return c.GoogleCredentialsFile != "" && c.GoogleTasksListID != ""
}

// getEnvWithDefault returns environment variable value or default if not set
func getEnvWithDefault(key, defaultValue string) string {
	if value := os.Getenv(key); value != "" {
		return value
	}
	return defaultValue
}

// getEnvAsInt returns environment variable as int or default if not set or invalid
func getEnvAsInt(key string, defaultValue int) int {
	valueStr := os.Getenv(key)
	if valueStr == "" {
		return defaultValue
	}

	value, err := strconv.Atoi(valueStr)
	if err != nil {
		return defaultValue
	}

	return value
}

// getEnvAsBool returns environment variable as bool or default if not set
func getEnvAsBool(key string, defaultValue bool) bool {
	valueStr := os.Getenv(key)
	if valueStr == "" {
		return defaultValue
	}

	value, err := strconv.ParseBool(valueStr)
	if err != nil {
		return defaultValue
	}

	return value
}