var yaml = require('js-yaml'),
  fs = require('fs');

module.exports = {

  asJson: function(spec) {
    try {
      return JSON.parse(spec);
    }
    catch (jsonException) {
      throw new SyntaxError(`Specification is not a valid JSON. ${jsonException}`);
    }
  },

  asYaml: function(spec) {
    try {
      return yaml.safeLoad(spec);
    }
    catch (yamlException) {
      throw new SyntaxError(`Specification is not a valid YAML. ${yamlException}`);
    }
  },

  validateSpec: function(spec) {

    // Checking for the all the required properties in the specification
    if (!spec.hasOwnProperty('openapi')) {
      return {
        result: false,
        reason: 'Specification must contain a semantic version number of the OAS specification'
      };
    }

    if (!spec.paths) {
      return {
        result: false,
        reason: 'Specification must contain Paths Object for the available operational paths'
      };
    }

    if (!spec.hasOwnProperty('info')) {
      return {
        result: false,
        reason: 'Specification must contain an Info Object for the meta-data of the API'
      };
    }

    if (!spec.info.hasOwnProperty('title')) {
      return {
        result: false,
        reason: 'Specification must contain a title in order to generate a collection'
      };
    }

    if (!spec.info.hasOwnProperty('version')) {
      return {
        result: false,
        reason: 'Specification must contain a semantic version number of the API in the Info Object'
      };
    }
    // Valid specification
    return {
      result: true,
      openapi: spec
    };
  },

  validateRoot: function(spec) {

    // Checking for the all the required properties needed in a root file
    if (!spec.hasOwnProperty('openapi')) {
      return {
        result: false,
        reason: 'Specification must contain a semantic version number of the OAS specification'
      };
    }

    if (!spec.paths) {
      return {
        result: false,
        reason: 'Specification must contain Paths Object for the available operational paths'
      };
    }

    if (!spec.hasOwnProperty('info')) {
      return {
        result: false,
        reason: 'Specification must contain an Info Object for the meta-data of the API'
      };
    }


    // Valid specification
    return {
      result: true,
      openapi: spec
    };
  },

  getOasObject: function(file) {
    let oasObj = file;

    if (typeof file === 'string') {
      try {
        oasObj = JSON.parse(file);
      }
      catch (jsonEx) {
        // Not direct JSON. Could be YAML
        try {
          oasObj = yaml.safeLoad(file);
        }
        catch (yamlEx) {
          // Not JSON or YAML
          return {
            result: false,
            reason: 'The input must be valid JSON or YAML'
          };
        }
        // valid YAML
      }
    }

    return oasObj;
  },

  getRootFiles: function(filesPathArray) {
    let rootFilesArray = [];

    filesPathArray.forEach((filePath) => {
      let file = fs.readFileSync(filePath.fileName, 'utf8'),
        oasObject = this.getOasObject(file);

      if (this.validateRoot(oasObject).result) {
        rootFilesArray.push(filePath.fileName);
      }
    });

    return rootFilesArray;
  }
};