// Environment variable loading and validation.

export function loadConfig() {
  const key = process.env.OPENAI_API_KEY;

  if (!key) {
    throw new Error('Configuration error: OPENAI_API_KEY is missing.');
  }

  const parseNum = (name, raw, fallback) => {
    if (raw === undefined || raw === '') return fallback;
    const n = Number(raw);
    if (isNaN(n) || !Number.isFinite(n) || n < 0) {
      throw new Error(
        `Configuration error: ${name} must be a positive number, got "${raw}".`
      );
    }
    return n;
  };

  const parseBool = (name, raw, fallback) => {
    if (raw === undefined || raw === '') return fallback;
    if (raw === 'true') return true;
    if (raw === 'false') return false;
    throw new Error(
      `Configuration error: ${name} must be true or false, got "${raw}".`
    );
  };

  return {
    openaiApiKey: key,
    openaiModel: process.env.OPENAI_MODEL || 'gpt-5.1',
    temperature: parseNum('OPENAI_TEMPERATURE', process.env.OPENAI_TEMPERATURE, 0.2),
    maxOutputTokens: parseNum('OPENAI_MAX_OUTPUT_TOKENS', process.env.OPENAI_MAX_OUTPUT_TOKENS, 2000),
    logLevel: process.env.CHATGPT_MCP_LOG_LEVEL || 'info',
    enableFileContext: parseBool('CHATGPT_MCP_ENABLE_FILE_CONTEXT', process.env.CHATGPT_MCP_ENABLE_FILE_CONTEXT, false),
    contextDir: process.env.CHATGPT_MCP_CONTEXT_DIR || './context',
    maxInputChars: parseNum('CHATGPT_MCP_MAX_INPUT_CHARS', process.env.CHATGPT_MCP_MAX_INPUT_CHARS, 30000),
    maxFileChars: parseNum('CHATGPT_MCP_MAX_FILE_CHARS', process.env.CHATGPT_MCP_MAX_FILE_CHARS, 12000),
    maxFiles: parseNum('CHATGPT_MCP_MAX_FILES', process.env.CHATGPT_MCP_MAX_FILES, 5),
    maxLogChars: parseNum('CHATGPT_MCP_MAX_LOG_CHARS', process.env.CHATGPT_MCP_MAX_LOG_CHARS, 10000),
    redactSecrets: parseBool('CHATGPT_MCP_REDACT_SECRETS', process.env.CHATGPT_MCP_REDACT_SECRETS, true),
    chatgptMcpProvider: process.env.CHATGPT_MCP_PROVIDER || 'openai',
    ollamaBaseUrl: process.env.OLLAMA_BASE_URL || 'http://localhost:11434',
    ollamaModel: process.env.OLLAMA_MODEL || 'qwen3:latest',
    ollamaTemperature: parseNum('OLLAMA_TEMPERATURE', process.env.OLLAMA_TEMPERATURE, 0.2),
    ollamaTimeout: parseNum('OLLAMA_TIMEOUT', process.env.OLLAMA_TIMEOUT, 60),
  };
}