import fs from 'fs-extra';
import { logInfo, logError } from './logger';
import type { GenerationConfig, TagConfig } from '../types';
import type { SwaggerAnalysis } from '../types';
import type { TagSummary } from '../types';
import type { ApiKeyInfo } from './environment-finder';

/**
 * Loads and validates a GenerationConfig from a JSON file.
 */
export function loadConfig(filePath: string): GenerationConfig {
  if (!fs.existsSync(filePath)) {
    logError(`Configuration file not found: ${filePath}`);
    process.exit(1);
  }

  const raw = fs.readFileSync(filePath, 'utf8');
  let config: GenerationConfig;

  try {
    config = JSON.parse(raw) as GenerationConfig;
  } catch {
    logError(`Invalid JSON in configuration file: ${filePath}`);
    process.exit(1);
  }

  if (!config.tags || typeof config.tags !== 'object') {
    logError('Configuration file must contain a "tags" object');
    process.exit(1);
  }

  for (const [tag, tagConfig] of Object.entries(config.tags)) {
    if (!tagConfig.baseUrl || typeof tagConfig.baseUrl !== 'string') {
      logError(`Tag "${tag}" must have a "baseUrl" string`);
      process.exit(1);
    }
    if (!Array.isArray(tagConfig.endpoints) || tagConfig.endpoints.length === 0) {
      logError(`Tag "${tag}" must have a non-empty "endpoints" array`);
      process.exit(1);
    }
  }

  return config;
}

/**
 * Builds a default GenerationConfig from a swagger analysis, including all tags
 * and all endpoints. Useful for --init-config to scaffold a config template.
 */
export function generateDefaultConfig(
  analysis: SwaggerAnalysis,
  tagSummaries: TagSummary[],
  cliOptions: {
    input: string;
    output: string;
    templates?: string;
    skipLint?: boolean;
    skipInstall?: boolean;
  },
  apiKeys: ApiKeyInfo[]
): GenerationConfig {
  const tags: Record<string, TagConfig> = {};

  for (const summary of tagSummaries) {
    const matchingKey = apiKeys.find((k) =>
      k.key.toLowerCase().includes(summary.tag.toLowerCase())
    );

    tags[summary.tag] = {
      baseUrl: matchingKey?.key || 'apiUrl',
      endpoints: summary.operations.map((op) => op.nickname)
    };
  }

  const config: GenerationConfig = {
    input: cliOptions.input,
    output: cliOptions.output,
    skipLint: cliOptions.skipLint ?? false,
    skipInstall: cliOptions.skipInstall ?? false,
    tags
  };

  if (cliOptions.templates) {
    config.templates = cliOptions.templates;
  }

  return config;
}

/**
 * Writes a GenerationConfig to a JSON file.
 */
export function writeConfig(config: GenerationConfig, filePath: string): void {
  fs.writeFileSync(filePath, JSON.stringify(config, null, 2) + '\n', 'utf8');
  logInfo(`Configuration file written to: ${filePath}`);
}

/**
 * Derives the selectionFilter (tag → endpoint nicknames) from a GenerationConfig.
 */
export function deriveSelectionFilter(config: GenerationConfig): Record<string, string[]> {
  const filter: Record<string, string[]> = {};
  for (const [tag, tagConfig] of Object.entries(config.tags)) {
    filter[tag] = [...tagConfig.endpoints];
  }
  return filter;
}

/**
 * Derives the tagApiKeyMap (tag → baseUrl key) from a GenerationConfig.
 */
export function deriveTagApiKeyMap(config: GenerationConfig): Record<string, string> {
  const map: Record<string, string> = {};
  for (const [tag, tagConfig] of Object.entries(config.tags)) {
    map[tag] = tagConfig.baseUrl;
  }
  return map;
}