import * as plugins from './plugins.js';
import type { IBinaryLocatorOptions, IRustBridgeLogger } from './interfaces/index.js';

const defaultLogger: IRustBridgeLogger = {
  log() {},
};

/**
 * Locates a Rust binary using a priority-ordered search strategy:
 * 1. Explicit binaryPath override
 * 2. Environment variable
 * 3. Platform-specific npm package
 * 4. Local development build paths
 * 5. System PATH
 */
export class RustBinaryLocator {
  private options: IBinaryLocatorOptions;
  private logger: IRustBridgeLogger;
  private cachedPath: string | null = null;

  constructor(options: IBinaryLocatorOptions, logger?: IRustBridgeLogger) {
    this.options = options;
    this.logger = logger || defaultLogger;
  }

  /**
   * Find the binary path.
   * Returns null if no binary is available.
   */
  public async findBinary(): Promise<string | null> {
    if (this.cachedPath !== null) {
      return this.cachedPath;
    }
    const path = await this.searchBinary();
    this.cachedPath = path;
    return path;
  }

  /**
   * Clear the cached binary path.
   */
  public clearCache(): void {
    this.cachedPath = null;
  }

  private async searchBinary(): Promise<string | null> {
    const { binaryName } = this.options;

    // 1. Explicit binary path override
    if (this.options.binaryPath) {
      if (await this.isExecutable(this.options.binaryPath)) {
        this.logger.log('info', `Binary found via explicit path: ${this.options.binaryPath}`);
        return this.options.binaryPath;
      }
      this.logger.log('warn', `Explicit binary path not executable: ${this.options.binaryPath}`);
    }

    // 2. Environment variable override
    if (this.options.envVarName) {
      const envPath = process.env[this.options.envVarName];
      if (envPath) {
        if (await this.isExecutable(envPath)) {
          this.logger.log('info', `Binary found via ${this.options.envVarName}: ${envPath}`);
          return envPath;
        }
        this.logger.log('warn', `${this.options.envVarName} set but not executable: ${envPath}`);
      }
    }

    // 3. Platform-specific npm package
    if (this.options.platformPackagePrefix) {
      const platformBinary = await this.findPlatformPackageBinary();
      if (platformBinary) {
        this.logger.log('info', `Binary found in platform package: ${platformBinary}`);
        return platformBinary;
      }
    }

    // 4. Local development build paths
    const localPaths = this.options.localPaths || [
      plugins.path.resolve(process.cwd(), `rust/target/release/${binaryName}`),
      plugins.path.resolve(process.cwd(), `rust/target/debug/${binaryName}`),
    ];
    for (const localPath of localPaths) {
      if (await this.isExecutable(localPath)) {
        this.logger.log('info', `Binary found at local path: ${localPath}`);
        return localPath;
      }
    }

    // 5. System PATH
    if (this.options.searchSystemPath !== false) {
      const systemPath = await this.findInPath(binaryName);
      if (systemPath) {
        this.logger.log('info', `Binary found in system PATH: ${systemPath}`);
        return systemPath;
      }
    }

    this.logger.log('error', `No binary '${binaryName}' found. Provide an explicit path, set an env var, install the platform package, or build from source.`);
    return null;
  }

  private async findPlatformPackageBinary(): Promise<string | null> {
    const { binaryName, platformPackagePrefix } = this.options;
    const platform = process.platform;
    const arch = process.arch;
    const packageName = `${platformPackagePrefix}-${platform}-${arch}`;

    try {
      const resolved = import.meta.resolve(`${packageName}/${binaryName}`);
      const packagePath = plugins.url.fileURLToPath(resolved);
      if (await this.isExecutable(packagePath)) {
        return packagePath;
      }
    } catch {
      // Package not installed - expected for development
    }
    return null;
  }

  private async isExecutable(filePath: string): Promise<boolean> {
    try {
      await plugins.fs.promises.access(filePath, plugins.fs.constants.X_OK);
      return true;
    } catch {
      return false;
    }
  }

  private async findInPath(binaryName: string): Promise<string | null> {
    const pathDirs = (process.env.PATH || '').split(plugins.path.delimiter);
    for (const dir of pathDirs) {
      const fullPath = plugins.path.join(dir, binaryName);
      if (await this.isExecutable(fullPath)) {
        return fullPath;
      }
    }
    return null;
  }
}