/**
 * Configuration management for Productboard MCP server
 * Supports multi-workspace setup following Jira MCP patterns
 */
import { readFileSync, existsSync } from 'fs';
import { join } from 'path';
import {
  MultiInstanceProductboardConfig,
  ProductboardInstanceConfig,
} from './types.js';
import { RATE_LIMITS } from './constants.js';

const CONFIG_FILE = '.productboard-config.json';

/**
 * Load configuration from file or environment variables
 */
export function loadConfig(): MultiInstanceProductboardConfig {
  // Check if we're in test mode
  if (process.env.NODE_ENV === 'test' && !process.env.PRODUCTBOARD_API_TOKEN) {
    // Return a mock configuration for tests
    return {
      instances: {
        test: {
          apiToken: 'mock-test-token',
          baseUrl: 'https://api.productboard.test',
          rateLimitPerMinute: RATE_LIMITS.DEFAULT_RATE_LIMIT_PER_MINUTE,
          workspaces: ['test-workspace'],
        },
      },
      workspaces: {
        'test-workspace': {
          instance: 'test',
          workspaceId: 'test-workspace-id',
        },
      },
      defaultInstance: 'test',
      toolCategories: {
        enabled: ['*'],
      },
    };
  }

  // Try to load from config file first
  const configPath = findConfigFile();
  if (configPath && existsSync(configPath)) {
    try {
      const configContent = readFileSync(configPath, 'utf-8');
      const config = JSON.parse(
        configContent
      ) as MultiInstanceProductboardConfig;
      return validateConfig(config);
    } catch (error) {
      console.error(`Failed to load config from ${configPath}:`, error);
    }
  }

  // Fallback to environment variables
  return createConfigFromEnvironment();
}

/**
 * Find config file in current directory or parent directories
 */
function findConfigFile(): string | null {
  let currentDir = process.cwd();

  while (currentDir !== '/') {
    const configPath = join(currentDir, CONFIG_FILE);
    if (existsSync(configPath)) {
      return configPath;
    }
    currentDir = join(currentDir, '..');
  }

  return null;
}

/**
 * Create configuration from environment variables
 */
function createConfigFromEnvironment(): MultiInstanceProductboardConfig {
  const apiToken = process.env.PRODUCTBOARD_API_TOKEN;
  const baseUrl =
    process.env.PRODUCTBOARD_BASE_URL || 'https://api.productboard.com';
  const workspaceId = process.env.PRODUCTBOARD_WORKSPACE_ID;

  if (!apiToken) {
    throw new Error('PRODUCTBOARD_API_TOKEN environment variable is required');
  }

  return {
    instances: {
      default: {
        apiToken,
        baseUrl,
        rateLimitPerMinute: 60,
        workspaces: workspaceId ? [workspaceId] : [],
      },
    },
    workspaces: workspaceId
      ? {
          [workspaceId]: {
            instance: 'default',
            workspaceId,
          },
        }
      : {},
    defaultInstance: 'default',
  };
}

/**
 * Validate configuration structure
 */
function validateConfig(
  config: MultiInstanceProductboardConfig
): MultiInstanceProductboardConfig {
  if (!config.instances || Object.keys(config.instances).length === 0) {
    throw new Error('Configuration must have at least one instance');
  }

  for (const [instanceName, instance] of Object.entries(config.instances)) {
    if (!instance.apiToken) {
      throw new Error(`Instance '${instanceName}' is missing apiToken`);
    }
    if (!instance.baseUrl) {
      instance.baseUrl = 'https://api.productboard.com';
    }
    if (!instance.rateLimitPerMinute) {
      instance.rateLimitPerMinute = RATE_LIMITS.DEFAULT_RATE_LIMIT_PER_MINUTE;
    }
  }

  if (!config.defaultInstance) {
    config.defaultInstance = Object.keys(config.instances)[0];
  }

  return config;
}

/**
 * Get instance configuration by name
 */
export function getInstance(
  config: MultiInstanceProductboardConfig,
  instanceName?: string
): ProductboardInstanceConfig {
  const name = instanceName || config.defaultInstance;
  if (!name || !config.instances[name]) {
    throw new Error(`Instance '${name}' not found in configuration`);
  }
  return config.instances[name];
}

/**
 * Get workspace configuration
 */
export function getWorkspace(
  config: MultiInstanceProductboardConfig,
  workspaceId: string
): { instance: string; workspaceId: string } {
  const workspace = config.workspaces?.[workspaceId];
  if (!workspace) {
    // Return default workspace config
    return {
      instance: config.defaultInstance!,
      workspaceId,
    };
  }
  // Ensure workspaceId is always set
  return {
    ...workspace,
    workspaceId: workspace.workspaceId || workspaceId,
  };
}