'use strict';

const SError     = require('./Error'),
    BbPromise    = require('bluebird'),
    fs           = require('fs'),
    fse          = BbPromise.promisifyAll(require('fs-extra')),
    path         = require('path'),
    wrench       = require('wrench'),
    _            = require('lodash');

/**
 * This is the base class that all Serverless Runtimes should extend.
 */


let SUtils;

class ServerlessRuntimeBase {

  constructor(S, name) {
    SUtils      = S.utils;
    this.S      = S;
    this.name   = name;
  }

  /**
   * Scaffold
   * - Scaffold the function in this runtime
   */

  scaffold(func) {
    return BbPromise.resolve();
  }

  /**
   * Run
   * - Run the function in this runtime
   */

  run(func) {
    return BbPromise.reject(new SError(`Runtime "${this.getName()}" should implement "run()" method`));
  }

  /**
   * Build
   * - Build the function in this runtime
   */

  build(func, stage, region) {
    return BbPromise.reject(new SError(`Runtime "${this.getName()}" should implement "build()" method`));
  }

  getName() {
    return this.name;
  }

  /**
   * Get ENV Vars
   * - Gets ENV vars for this function and sets some defaults
   */

  getEnvVars(func, stage, region) {

    const envVars = func.toObjectPopulated({stage, region}).environment,
        project   = this.S.getProject();

    const defaultVars = {
      SERVERLESS_PROJECT:          project.getName(),
      SERVERLESS_STAGE:            stage,
      SERVERLESS_REGION:           region,
      SERVERLESS_DATA_MODEL_STAGE: stage ? project.getStage(stage).getName() : stage
    };

    return BbPromise.resolve(_.defaults(defaultVars, envVars));
  }

  /**
   * Create Dist Dir
   * - Creates a distribution folder for this function in _meta/_tmp
   */

  createDistDir(funcName) {

    let d         = new Date(),
        pathDist  = this.S.getProject().getRootPath('_meta', '_tmp', funcName + '@' + d.getTime());

    return new BbPromise(function(resolve, reject) {
      try {
        fse.mkdirsSync(path.dirname(pathDist));
      } catch (e) {
        reject(new SError(`Error creating parent folders when writing this file: ${pathDist}
      ${e.message}`));
      }

      resolve(pathDist);
    });
  }

  /**
   * Copy Function
   * - Copies function to dist dir
   */

  copyFunction(func, pathDist, stage, region) {
    return BbPromise.try(() => {
      // Status
      SUtils.sDebug(`"${stage} - ${region} - ${func.getName()}": Copying in dist dir ${pathDist}`);

      // Extract the root of the lambda package from the handler property
      let handlerFullPath = func.getRootPath(func.handler.split('/')[func.handler.split('/').length - 1]).replace(/\\/g, '/');

      // Check handler is correct
      if (handlerFullPath.indexOf(func.handler) == -1) {
        throw new SError('This function\'s handler is invalid and not in the file system: ' + func.handler);
      }

      let packageRoot = handlerFullPath.replace(func.handler, '');

      return wrench.copyDirSyncRecursive(packageRoot, pathDist, {
        exclude: this._processExcludePatterns(func, pathDist, stage, region)
      });
    });
  }

  /**
   * Install Dependencies
   */

  installDependencies(dir ) {
    return BbPromise.reject(new SError(`Runtime "${this.getName()}" should implement "installDependencies()" method`));
  }

  /**
   * Generate Paths
   * - Generate and return an array of paths of the function
   */

  generatePaths(func, pathDist) {

    let compressPaths = [],
        ignore        = ['.DS_Store'],
        stats,
        fullPath;

    // Zip up whatever is in back
    let includePaths = ['.'];

    includePaths.forEach(p => {

      try {
        fullPath = path.resolve(path.join(pathDist, p));
        stats    = fs.lstatSync(fullPath);
      } catch (e) {
        console.error('Cant find includePath ', p, e);
        throw e;
      }

      if (stats.isFile()) {

        compressPaths.push({
          name: p,
          path: fullPath
        });

      } else if (stats.isDirectory()) {

        let dirname = path.basename(p);

        wrench
            .readdirSyncRecursive(fullPath)
            .forEach(file => {

              // Ignore certain files
              for (let i = 0; i < ignore.length; i++) {
                if (file.toLowerCase().indexOf(ignore[i]) > -1) return;
              }

              let filePath = path.join(fullPath, file);
              if (fs.lstatSync(filePath).isFile()) {

                let pathInZip = path.join(dirname, file);

                compressPaths.push({
                  name: pathInZip,
                  path: filePath
                });
              }
            });
      }
    });

    return BbPromise.resolve(compressPaths);
  }

  /**
   * Process Exclude Patterns
   * - Process exclude patterns in function.custom.excludePatterns
   */

  _processExcludePatterns(func, pathDist, stage, region) {
    // Copy entire test project to temp folder, don't include anything in excludePatterns
    let excludePatterns = func.custom.excludePatterns || [];

    return function(name, prefix) {

      if (!excludePatterns.length) { return false;}

      let relPath = path.join(prefix.replace(pathDist, ''), name);

      return excludePatterns.some(sRegex => {
        relPath = (relPath.charAt(0) == path.sep) ? relPath.substr(1) : relPath;

        let re        = new RegExp(sRegex),
            matches     = re.exec(relPath),
            willExclude = (matches && matches.length > 0);

        if (willExclude) {
          SUtils.sDebug(`"${stage} - ${region} - ${func.name}": Excluding - ${relPath}`);
        }

        return willExclude;
      });
    }
  }
}


module.exports = ServerlessRuntimeBase;