/**
 * Plugin Manager with sophisticated dependency resolution using topological sorting
 * 
 * This is a reimplementation of https://www.npmjs.com/package/js-plugin with additional features,
 * designed as a superset that maintains compatibility with code written for js-plugin.
 *
 * ## Basic Usage Example
 * 
 * ```javascript
 * import { PluginManager } from './plugin-manager.js';
 * 
 * const manager = new PluginManager();
 * 
 * // Register plugins
 * manager.register({
 *   name: 'logger',
 *   config: { level: 'info' },
 *   install() { console.log('Logger installed'); }
 * });
 * 
 * manager.register({
 *   name: 'database', 
 *   deps: ['logger'],
 *   config: { timeout: 5000 },
 *   install() { console.log('Database installed'); }
 * });
 * 
 * // Invoke extension points (functions)
 * await manager.invoke('install');  // Calls install() on all plugins in dependency order
 * 
 * // Collect configuration values (no-call)
 * const timeouts = await manager.invoke('!config.timeout');  // Returns [undefined, 5000]
 * const levels = await manager.invoke('!config.level');      // Returns ['info', undefined]
 * 
 * // Error handling
 * await manager.invoke('install!');  // Throws on first plugin error
 * ```
 * 
 * ## Endpoint Invocation Flags
 * 
 * Endpoint names support special flag prefixes and suffixes to control invocation behavior:
 * 
 * ### No-Call Flag (`!` prefix)
 * - **Usage**: `manager.invoke("!config.timeout")`
 * - **Purpose**: Retrieve property values without calling functions
 * - **Behavior**: Returns the value at the endpoint path from each plugin
 * - **Example**: Collect configuration values or status data across plugins
 * 
 * ### Throw Flag (`!` suffix)  
 * - **Usage**: `manager.invoke("install!")`
 * - **Purpose**: Throw errors immediately instead of collecting them
 * - **Behavior**: First plugin error terminates execution and rethrows
 * - **Example**: Critical operations where failures should halt processing
 * 
 * Flags can be combined. 
 * 
 * The no-call flag (`!`) converts function invocation into value retrieval, enabling
 * data collection workflows using the same plugin traversal and dependency ordering.
 */

import Plugin from './plugin-base.js';

/**
 * The minimal plugin configuration object
 * @typedef {object & Record<string, any>} PluginConfig
 * @property {string} name - The name of the plugin
 * @property {string[]} [deps] - The names of the plugins this plugin depends on
 * @property {any} [initialize] - Optional initialization function 
 */


/**
 * Options for plugin endpoint invocation
 * @typedef {Object} InvokeOptions
 * @property {boolean} [throws] - If true, an error in one of the endpoints throws the invocation
 * @property {boolean} [nocall] - If true, get the extension points value rather than trying to call it as a function
 * @property {number} [timeout] - Timeout override for this invocation (milliseconds)
 * @property {'parallel'|'sequential'} [mode] - Execution mode: 'parallel' (default) or 'sequential'
 * @property {'first'|'values'|'full'} [result] - Form of result: 
 *    'first' (default) returns the first fulfilled response, 
 *    'values' returns the values of all fulfilled responses, 
 *    'full' returns an array of {status:string, value:any} objects 
 * @property {boolean} [debug] - If true, output verbose debug messages
 */

/**
 * @typedef {({status: 'fulfilled', value: any} | {status: 'rejected', reason: Error})} InvocationResult
 */

/**
 * Plugin Manager with dependency resolution
 */
export class PluginManager {
  /**
   * @param {InvokeOptions} options 
   */
  constructor(options = {}) {
    /** @type {Map<string, PluginConfig>} */
    this.pluginsByName = new Map();

    /** @type {Map<string, any>} */
    this.pluginApis = new Map();

    /** @type {PluginConfig[]} */
    this.registeredPlugins = [];

    /** @type {PluginConfig[]} */
    this.dependencyOrderedPlugins = [];

    /** @type {Map<string, PluginConfig[]>} */
    this.endpointCache = new Map();

    /** @type {InvokeOptions} */
    this.config = {
      timeout: options.timeout || 2000,
      throws: options.throws || false,
      mode: options.mode || "parallel",
      result: options.result || "first"
    };

    /** @type {boolean} */
    this.debug = options.debug || false;

  }

  /**
   * Register a plugin with dependency resolution
   * @param {PluginConfig|Plugin} plugin - Plugin to register (can be Plugin instance or config object)
   * @throws {Error} If plugin is invalid or creates circular dependencies
   */
  register(plugin) {
    // Validate plugin
    if (!plugin || typeof plugin !== 'object') {
      throw new Error('Plugin must be an object');
    }

    // Handle Plugin class instances - convert to plugin object
    let pluginConfig;
    if (plugin instanceof Plugin) {
      if (this.debug) {
        console.log(`Converting Plugin instance '${plugin.name}' to plugin object`);
      }
      pluginConfig = this.convertPluginInstance(plugin);
    } else {
      pluginConfig = plugin;
    }

    if (!pluginConfig.name || typeof pluginConfig.name !== 'string') {
      console.error('Invalid plugin:', pluginConfig);
      throw new Error('Every plugin must have a name property');
    }

    if (this.pluginsByName.has(pluginConfig.name)) {
      throw new Error(`Plugin "${pluginConfig.name}" is already registered`);
    }

    // Normalize dependencies
    const normalizedPlugin = {
      ...pluginConfig,
      deps: Array.isArray(pluginConfig.deps) ? pluginConfig.deps : []
    };

    // Register plugin
    this.pluginsByName.set(pluginConfig.name, normalizedPlugin);
    this.registeredPlugins.push(normalizedPlugin);

    // Store public API: Plugin instances use getApi() (defaults to the instance itself);
    // object plugins use .api if present
    if (plugin instanceof Plugin) {
      this.pluginApis.set(pluginConfig.name, plugin.getApi());
    } else if (pluginConfig.api !== undefined) {
      this.pluginApis.set(pluginConfig.name, pluginConfig.api);
    } else {
      this.pluginApis.set(pluginConfig.name, pluginConfig);
    }

    // Clear caches
    this.endpointCache.clear();
    this.dependencyOrderedPlugins = [];

    // Recompute dependency order
    this.computeDependencyOrder();

    // Call initialize function if present
    if (plugin instanceof Plugin) {
      plugin.initialize();
    }

    if (this.debug) {
      console.log(`Registered plugin '${plugin.name}' with dependencies: [${normalizedPlugin.deps.join(', ') || 'none'}]`);
    }
  }

  /**
   * Unregister a plugin
   * @param {string} pluginName - Name of plugin to unregister
   * @throws {Error} If plugin doesn't exist
   */
  unregister(pluginName) {
    const plugin = this.pluginsByName.get(pluginName);
    if (!plugin) {
      throw new Error(`Plugin "${pluginName}" doesn't exist`);
    }

    // Remove from all collections
    this.pluginsByName.delete(pluginName);
    this.pluginApis.delete(pluginName);
    this.registeredPlugins = this.registeredPlugins.filter(p => p.name !== pluginName);

    // Clear caches and recompute order
    this.endpointCache.clear();
    this.dependencyOrderedPlugins = [];
    this.computeDependencyOrder();
  }

  /**
   * Get a specific plugin by name
   * @param {string} pluginName - Name of plugin to retrieve
   * @returns {PluginConfig|undefined} Plugin definition or undefined if not found
   */
  getPlugin(pluginName) {
    return this.pluginsByName.get(pluginName);
  }

  /**
   * Get the public API for a registered plugin by name.
   * For class-based plugins this is the Plugin instance; for object plugins it is the
   * `api` field of the plugin descriptor (or the descriptor itself as a fallback).
   * @param {string} name - Plugin name
   * @returns {any} The plugin's public API, or undefined if not registered
   */
  getDependency(name) {
    return this.pluginApis.get(name);
  }

  /**
   * Get plugins that implement a specific endpoint in dependency order
   * @param {string} endpoint - Endpoint path (e.g., 'install', 'state.update')
   * @returns {PluginConfig[]} Array of plugins that implement the endpoint
   */
  getPlugins(endpoint = '.') {
    // Check cache first
    if (this.endpointCache.has(endpoint)) {
      return this.endpointCache.get(endpoint) || [];
    }

    // Filter plugins that have the endpoint and all their dependencies are satisfied
    const filteredPlugins = this.dependencyOrderedPlugins.filter(plugin => {
      // Check if any dependencies are missing
      if (plugin.deps && plugin.deps.length > 0) {
        const missingDependencies = plugin.deps.filter(depName => !this.pluginsByName.has(depName));
        if (missingDependencies.length > 0) {
          console.warn(`Plugin ${plugin.name} is not loaded because its dependencies do not exist: ${missingDependencies.join(', ')}`);
          return false;
        }
      }

      // Check if plugin has the requested endpoint
      if (endpoint === '.') {
        return true; // All plugins
      }
      return this.hasEndpoint(plugin, endpoint);
    });

    // Cache the result
    this.endpointCache.set(endpoint, filteredPlugins);
    return filteredPlugins;
  }

  /**
   * Check if a plugin has a specific endpoint
   * @param {PluginConfig} plugin - Plugin to check
   * @param {string} endpoint - Endpoint path to check
   * @returns {boolean} True if plugin has the endpoint
   * @private
   */
  hasEndpoint(plugin, endpoint) {
    const pathParts = endpoint.split('.');
    let current = plugin;

    for (const part of pathParts) {
      if (current == null || !(part in current)) {
        return false;
      }
      current = current[part];
    }

    return true;
  }

  /**
   * Get value at endpoint path in plugin
   * @param {PluginConfig} plugin - Plugin object
   * @param {string} endpoint - Endpoint path
   * @returns {*} Value at endpoint or undefined
   * @private
   */
  getEndpointValue(plugin, endpoint) {
    const pathParts = endpoint.split('.');
    let current = plugin;

    for (const part of pathParts) {
      if (current == null || !(part in current)) {
        return undefined;
      }
      current = current[part];
    }

    return current;
  }

  /**
   * Invoke an endpoint on all plugins that implement it, in dependency order. The invocation can be done in parallel or sequentially. 
   * @param {string} endpoint - Endpoint to invoke
   * @param {*|Array} [args] - Arguments to pass to endpoint functions. If array, spread as parameters; if not array, pass as single parameter
   * @param {InvokeOptions} [options] - Optional configuration for this invocation
   * @returns {Promise<InvocationResult[] | any[] | any>} Result formatted depending on options.result
   */
  async invoke(endpoint, args = [], options = {}) {
    if (!endpoint) {
      throw new Error('Invoke requires an endpoint argument');
    }

    // Convert args to array for apply() - if it's already an array, use it; otherwise wrap in array
    const invokeArgs = Array.isArray(args) ? args : [args];

    // Parse endpoint flags
    const isNoCall = options.nocall || /^!/.test(endpoint);
    const shouldThrow = options.throws || /!$/.test(endpoint) || this.config.throws;
    const cleanEndpoint = endpoint.replace(/^!|!$/g, '');

    // Get the parent object path for method context
    const endpointParts = cleanEndpoint.split('.');
    endpointParts.pop(); // Remove the method name
    const contextPath = endpointParts.join('.');

    // Get plugins that implement this endpoint
    const plugins = this.getPlugins(cleanEndpoint);

    // invocation mode
    const mode = options.mode || this.config.mode;

    switch (mode) {
      case 'sequential':
        // Sequential execution - respects dependency order

        /** @type {InvocationResult[]} */
        const results = [];

        for (const plugin of plugins) {
          const method = this.getEndpointValue(plugin, cleanEndpoint);

          if (typeof method !== 'function' || isNoCall) {
            results.push({ status: 'fulfilled', value: method });
            continue;
          }

          try {
            if (this.debug) {
              console.log('Before', plugin.name, cleanEndpoint, invokeArgs);
            }

            // Get the context object for the method
            const context = contextPath ? this.getEndpointValue(plugin, contextPath) : plugin;

            // Invoke the method with proper context
            const result = await method.apply(context, invokeArgs);

            if (this.debug) {
              console.log('After', plugin.name, cleanEndpoint, 'completed');
            }
            results.push({ status: 'fulfilled', value: result });
          } catch (error) {
            const errorMessage = `Failed to invoke plugin: ${plugin.name}!${cleanEndpoint}`;
            console.error(errorMessage, error);

            if (shouldThrow) {
              throw error;
            }

            results.push({ status: 'rejected', reason: error });
          }
        }

        return this._processResult(results, options);

      case 'parallel':
      default:

        // Parallel execution (default behavior)

        const promises = plugins.map(async plugin => {
          const method = this.getEndpointValue(plugin, cleanEndpoint);

          if (typeof method !== 'function' || isNoCall) {
            return method;
          }

          if (this.debug) {
            console.log('Before', plugin.name, cleanEndpoint, invokeArgs);
          }

          // Get the context object for the method
          const context = contextPath ? this.getEndpointValue(plugin, contextPath) : plugin;

          // Invoke the method with proper context
          const result = method.apply(context, invokeArgs);

          if (this.debug) {
            console.log('After', plugin.name, cleanEndpoint, 'completed');
          }
          return result;
        });

        // Set up timeout mechanism
        const timeout = options.timeout !== undefined ? options.timeout : this.config.timeout;
        const controller = new AbortController();
        const timeoutId = setTimeout(() => {
          controller.abort();
        }, timeout);

        try {
          /** @type {InvocationResult[]} */
          const result = await Promise.allSettled(promises);

          // Handle throwing behavior before result processing
          if (shouldThrow) {
            const firstRejected = result.find(({ status }) => status === "rejected");
            if (firstRejected ) {
              // @ts-ignore
              throw firstRejected.reason;
            }
          }

          return this._processResult(result, options);
        } finally {
          clearTimeout(timeoutId);
        }
    }
    //throw new Error(`Invalid option.result: '${options.result}'`)

  }
  /**
   * Processes the results of the endpoint invocations
   * @param {InvocationResult[]} result The result of the invocation
   * @param {InvokeOptions} options 
   * @return {any} {@see {InvocationOptions}}
   */
  _processResult(result, options = {}) {
    const resultMode = options.result || this.config.result || 'full';
    
    switch (resultMode) {
      case 'first':
        const firstFulfilled = result.find(({ status }) => status === "fulfilled");
        // @ts-ignore
        return firstFulfilled ? firstFulfilled.value : undefined;
      case 'values':
        // Return only the values from fulfilled results
        return result
          .filter(({ status }) => status === "fulfilled")
          // @ts-ignore
          .map(({ value }) => value);
      case 'full':
      default:
        return result;
    }
  }

  /**
   * Compute dependency-resolved plugin order using topological sort
   * @throws {Error} If circular dependencies are detected
   * @private
   */
  computeDependencyOrder() {
    const plugins = [...this.registeredPlugins];
    const resolved = [];
    const visiting = new Set();
    const visited = new Set();

    /**
     * Depth-first search for topological sorting
     * @param {PluginConfig} plugin - Plugin to visit
     * @param {string[]} path - Current dependency path (for circular dependency detection)
     */
    const visit = (plugin, path = []) => {
      if (visiting.has(plugin.name)) {
        const cycle = [...path, plugin.name].join(' → ');
        throw new Error(`Circular dependency detected: ${cycle}`);
      }

      if (visited.has(plugin.name)) {
        return; // Already processed
      }

      visiting.add(plugin.name);

      // Visit all dependencies first
      for (const depName of plugin.deps || []) {
        const dependency = this.pluginsByName.get(depName);
        if (dependency) {
          visit(dependency, [...path, plugin.name]);
        }
        // Missing dependencies are handled in getPlugins()
      }

      visiting.delete(plugin.name);
      visited.add(plugin.name);
      resolved.push(plugin);
    };

    // Visit all plugins
    for (const plugin of plugins) {
      if (!visited.has(plugin.name)) {
        visit(plugin);
      }
    }

    this.dependencyOrderedPlugins = resolved;

    // Debug output
    const pluginNames = resolved.map(p => p.name);
    if (this.debug) {
      console.log(`🔗 Plugin dependency order: ${pluginNames.join(' → ')}`);
    }
  }

  /**
   * Sort an array by a property (utility method)
   * @param {Array} array - Array to sort
   * @param {string} [sortProperty='order'] - Property to sort by
   */
  sort(array, sortProperty = 'order') {
    array.sort((a, b) => {
      const orderA = a.hasOwnProperty(sortProperty) ? a[sortProperty] : 1000000;
      const orderB = b.hasOwnProperty(sortProperty) ? b[sortProperty] : 1000000;
      return orderA - orderB;
    });
  }

  /**
   * Process raw plugins array (utility method for pre-processing)
   * @param {Function} callback - Function to process the plugins array
   */
  processRawPlugins(callback) {
    callback(this.registeredPlugins);
    this.endpointCache.clear();
    this.computeDependencyOrder();
  }

  /**
   * Convert Plugin instance to plugin object using getExtensionPoints() method
   * @param {Plugin} pluginInstance - Plugin instance to convert
   * @returns {Object} Plugin configuration object
   * @private
   */
  convertPluginInstance(pluginInstance) {
    const pluginObject = {
      name: pluginInstance.name,
      deps: [...pluginInstance.deps], // Create a copy to avoid reference issues
    };

    const getPointsFn = pluginInstance.getExtensionPoints;
    if (typeof getPointsFn === 'function') {
      const endpoints = getPointsFn.call(pluginInstance);

      // Apply endpoint mappings to plugin object using dot notation
      for (const [endpointPath, method] of Object.entries(endpoints)) {
        this.setNestedProperty(pluginObject, endpointPath, method);
      }
    }

    return pluginObject;
  }

  /**
   * Set nested property in object using dot notation path
   * @param {Object} obj - Object to set property on
   * @param {string} path - Dot notation path
   * @param {*} value - Value to set
   * @private
   */
  setNestedProperty(obj, path, value) {
    const pathParts = path.split('.');
    let current = obj;

    for (let i = 0; i < pathParts.length - 1; i++) {
      const part = pathParts[i];
      if (!(part in current)) {
        current[part] = {};
      }
      current = current[part];
    }

    current[pathParts[pathParts.length - 1]] = value;
  }

}

// Export the class
export default PluginManager;