/**
 * Configuration Loader
 * 
 * Handles loading and parsing of the Iris configuration file (iris-config.yaml).
 * 
 * @module config/config-loader
 */

import fs from 'fs/promises'
import yaml from 'js-yaml'
import type { IrisConfig } from './types.js'

const DEFAULT_CONFIG_PATHS = [
    'iris-config.yaml',
    'iris-config.yml',
    '.iris/config.yaml',
    '.iris/config.yml',
    'config/iris-config.yaml'
]

/**
 * Load Iris configuration from file
 * 
 * @param configPath - Optional specific path to config file
 * @returns Parsed configuration or default empty config
 */
export async function loadIrisConfig(configPath?: string): Promise<IrisConfig> {
    let loadedPath: string | null = null

    if (configPath) {
        if (await fileExists(configPath)) {
            loadedPath = configPath
        } else {
            throw new Error(`Configuration file not found at: ${configPath}`)
        }
    } else {
        // Search default paths
        for (const p of DEFAULT_CONFIG_PATHS) {
            if (await fileExists(p)) {
                loadedPath = p
                break
            }
        }
    }

    if (!loadedPath) {
        // Return default config if no file found
        return {
            optimization: {
                strategy: ['grid']
            },
            storage: {
                backend: ['agentdb']
            }
        }
    }

    console.log(`📄 Loading config from: ${loadedPath}`)
    
    try {
        const content = await fs.readFile(loadedPath, 'utf-8')
        const config = yaml.load(content) as IrisConfig
        return validateAndNormalize(config)
    } catch (error) {
        throw new Error(`Failed to parse configuration file: ${error instanceof Error ? error.message : String(error)}`)
    }
}

async function fileExists(path: string): Promise<boolean> {
    try {
        await fs.access(path)
        return true
    } catch {
        return false
    }
}

function validateAndNormalize(config: IrisConfig): IrisConfig {
    // Ensure essential objects exist
    if (!config.optimization) config.optimization = {}
    if (!config.storage) config.storage = {}

    // Set defaults
    if (!config.optimization.strategy) {
        config.optimization.strategy = ['grid']
    }
    
    // Normalize search space if present
    if (config.optimization.searchSpace && !config.optimization.searchSpace.parameters) {
        config.optimization.searchSpace.parameters = []
    }

    return config
}