package config

import (
	"encoding/json"
	"fmt"
	"os"
)

// Config represents the application configuration
type Config struct {
	DataSource DataSourceConfig `json:"data_source"`
	LLM        LLMConfig        `json:"llm"`
	OutputDir  string           `json:"output_dir"`
	BatchSize  int              `json:"batch_size"`
	APIKey     string           `json:"api_key"`
}

// DataSourceConfig contains configuration for data source
type DataSourceConfig struct {
	URL string `json:"url"`
}

// LLMConfig contains configuration for LLM provider
type LLMConfig struct {
	Provider string              `json:"provider"` // "openrouter" or "lmstudio"
	Model    string              `json:"model"`
	APIKey   string              `json:"api_key,omitempty"`   // For OpenRouter
	BaseURL  string              `json:"base_url,omitempty"`  // For LM Studio
}

// Load loads configuration from a JSON file
func Load(path string) (*Config, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("reading config file: %w", err)
	}

	var cfg Config
	if err := json.Unmarshal(data, &cfg); err != nil {
		return nil, fmt.Errorf("parsing config file: %w", err)
	}

	return &cfg, nil
}

// Validate validates the configuration
func (c *Config) Validate() error {
	if c.DataSource.URL == "" {
		return fmt.Errorf("data_source.url is required")
	}

	if c.LLM.Provider != "openrouter" && c.LLM.Provider != "lmstudio" {
		return fmt.Errorf("llm.provider must be 'openrouter' or 'lmstudio'")
	}

	if c.LLM.Model == "" {
		return fmt.Errorf("llm.model is required")
	}

	if c.LLM.Provider == "openrouter" && c.LLM.APIKey == "" {
		return fmt.Errorf("llm.api_key is required for openrouter provider")
	}

	if c.LLM.Provider == "lmstudio" && c.LLM.BaseURL == "" {
		return fmt.Errorf("llm.base_url is required for lmstudio provider")
	}

	if c.OutputDir == "" {
		return fmt.Errorf("output_dir is required")
	}

	if c.BatchSize <= 0 {
		return fmt.Errorf("batch_size must be greater than 0")
	}

	if c.APIKey == "" {
		return fmt.Errorf("api_key is required")
	}

	return nil
}