package config

import (
	"fmt"
	"os"
	"path/filepath"

	"gopkg.in/yaml.v3"
)

// Config holds the application configuration
type Config struct {
	// LLM Configuration
	APIURL      string `yaml:"api_url"`
	Model       string `yaml:"model"`
	ContextSize int    `yaml:"context_size"`
	APIKey      string `yaml:"api_key"`

	// System Prompt
	Prompt string `yaml:"prompt"`

	// MCP Server Configuration
	MCPServers map[string]MCPServer `yaml:"mcp_servers"`
}

// MCPServer represents a single MCP server configuration (stdio transport only)
type MCPServer struct {
	Command string            `yaml:"command"`
	Args    []string          `yaml:"args,omitempty"`
	Env     map[string]string `yaml:"env,omitempty"`
}

// Load reads and parses the YAML configuration file from ~/.config/tell-me.yaml
func Load() (*Config, error) {
	// Get home directory
	homeDir, err := os.UserHomeDir()
	if err != nil {
		return nil, fmt.Errorf("failed to get home directory: %w", err)
	}

	// Build config path
	configPath := filepath.Join(homeDir, ".config", "tell-me.yaml")

	// Check if config file exists
	if _, err := os.Stat(configPath); os.IsNotExist(err) {
		return nil, fmt.Errorf("config file not found at %s. Please create it from tell-me.yaml.example", configPath)
	}

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

	// Parse YAML
	var cfg Config
	if err := yaml.Unmarshal(data, &cfg); err != nil {
		return nil, fmt.Errorf("failed to parse config file: %w", err)
	}

	// Set defaults
	if cfg.ContextSize == 0 {
		cfg.ContextSize = 16000
	}

	// Validate required fields
	if cfg.APIURL == "" {
		return nil, fmt.Errorf("api_url is required in config")
	}
	if cfg.Model == "" {
		return nil, fmt.Errorf("model is required in config")
	}
	if cfg.Prompt == "" {
		return nil, fmt.Errorf("prompt is required in config")
	}

	return &cfg, nil
}