"use strict";

var inherits = require('inherits');
inherits(PouchError, Error);

function PouchError(opts) {
  Error.call(opts.reason);
  this.status = opts.status;
  this.name = opts.error;
  this.message = opts.reason;
  this.error = true;
}

PouchError.prototype.toString = function () {
  return JSON.stringify({
    status: this.status,
    name: this.name,
    message: this.message
  });
};

exports.UNAUTHORIZED = new PouchError({
  status: 401,
  error: 'unauthorized',
  reason: "Name or password is incorrect."
});

exports.MISSING_BULK_DOCS = new PouchError({
  status: 400,
  error: 'bad_request',
  reason: "Missing JSON list of 'docs'"
});

exports.MISSING_DOC = new PouchError({
  status: 404,
  error: 'not_found',
  reason: 'missing'
});

exports.REV_CONFLICT = new PouchError({
  status: 409,
  error: 'conflict',
  reason: 'Document update conflict'
});

exports.INVALID_ID = new PouchError({
  status: 400,
  error: 'invalid_id',
  reason: '_id field must contain a string'
});

exports.MISSING_ID = new PouchError({
  status: 412,
  error: 'missing_id',
  reason: '_id is required for puts'
});

exports.RESERVED_ID = new PouchError({
  status: 400,
  error: 'bad_request',
  reason: 'Only reserved document ids may start with underscore.'
});

exports.NOT_OPEN = new PouchError({
  status: 412,
  error: 'precondition_failed',
  reason: 'Database not open'
});

exports.UNKNOWN_ERROR = new PouchError({
  status: 500,
  error: 'unknown_error',
  reason: 'Database encountered an unknown error'
});

exports.BAD_ARG = new PouchError({
  status: 500,
  error: 'badarg',
  reason: 'Some query argument is invalid'
});

exports.INVALID_REQUEST = new PouchError({
  status: 400,
  error: 'invalid_request',
  reason: 'Request was invalid'
});

exports.QUERY_PARSE_ERROR = new PouchError({
  status: 400,
  error: 'query_parse_error',
  reason: 'Some query parameter is invalid'
});

exports.DOC_VALIDATION = new PouchError({
  status: 500,
  error: 'doc_validation',
  reason: 'Bad special document member'
});

exports.BAD_REQUEST = new PouchError({
  status: 400,
  error: 'bad_request',
  reason: 'Something wrong with the request'
});

exports.NOT_AN_OBJECT = new PouchError({
  status: 400,
  error: 'bad_request',
  reason: 'Document must be a JSON object'
});

exports.DB_MISSING = new PouchError({
  status: 404,
  error: 'not_found',
  reason: 'Database not found'
});

exports.IDB_ERROR = new PouchError({
  status: 500,
  error: 'indexed_db_went_bad',
  reason: 'unknown'
});

exports.WSQ_ERROR = new PouchError({
  status: 500,
  error: 'web_sql_went_bad',
  reason: 'unknown'
});

exports.LDB_ERROR = new PouchError({
  status: 500,
  error: 'levelDB_went_went_bad',
  reason: 'unknown'
});

exports.FORBIDDEN = new PouchError({
  status: 403,
  error: 'forbidden',
  reason: 'Forbidden by design doc validate_doc_update function'
});

exports.INVALID_REV = new PouchError({
  status: 400,
  error: 'bad_request',
  reason: 'Invalid rev format'
});

exports.FILE_EXISTS = new PouchError({
  status: 412,
  error: 'file_exists',
  reason: 'The database could not be created, the file already exists.'
});

exports.MISSING_STUB = new PouchError({
  status: 412,
  error: 'missing_stub'
});

exports.error = function (error, reason, name) {
  function CustomPouchError(reason) {
    // inherit error properties from our parent error manually
    // so as to allow proper JSON parsing.
    /* jshint ignore:start */
    for (var p in error) {
      if (typeof error[p] !== 'function') {
        this[p] = error[p];
      }
    }
    /* jshint ignore:end */
    if (name !== undefined) {
      this.name = name;
    }
    if (reason !== undefined) {
      this.reason = reason;
    }
  }
  CustomPouchError.prototype = PouchError.prototype;
  return new CustomPouchError(reason);
};

// Find one of the errors defined above based on the value
// of the specified property.
// If reason is provided prefer the error matching that reason.
// This is for differentiating between errors with the same name and status,
// eg, bad_request.
exports.getErrorTypeByProp = function (prop, value, reason) {
  var errors = exports;
  var keys = Object.keys(errors).filter(function (key) {
    var error = errors[key];
    return typeof error !== 'function' && error[prop] === value;
  });
  var key = reason && keys.filter(function (key) {
        var error = errors[key];
        return error.message === reason;
      })[0] || keys[0];
  return (key) ? errors[key] : null;
};

exports.generateErrorFromResponse = function (res) {
  var error, errName, errType, errMsg, errReason;
  var errors = exports;

  errName = (res.error === true && typeof res.name === 'string') ?
              res.name :
              res.error;
  errReason = res.reason;
  errType = errors.getErrorTypeByProp('name', errName, errReason);

  if (res.missing ||
      errReason === 'missing' ||
      errReason === 'deleted' ||
      errName === 'not_found') {
    errType = errors.MISSING_DOC;
  } else if (errName === 'doc_validation') {
    // doc validation needs special treatment since
    // res.reason depends on the validation error.
    // see utils.js
    errType = errors.DOC_VALIDATION;
    errMsg = errReason;
  } else if (errName === 'bad_request' && errType.message !== errReason) {
    // if bad_request error already found based on reason don't override.

    // attachment errors.
    if (errReason.indexOf('unknown stub attachment') === 0) {
      errType = errors.MISSING_STUB;
      errMsg = errReason;
    } else {
      errType = errors.BAD_REQUEST;
    }
  }

  // fallback to error by statys or unknown error.
  if (!errType) {
    errType = errors.getErrorTypeByProp('status', res.status, errReason) ||
                errors.UNKNOWN_ERROR;
  }

  error = errors.error(errType, errReason, errName);

  // Keep custom message.
  if (errMsg) {
    error.message = errMsg;
  }

  // Keep helpful response data in our error messages.
  if (res.id) {
    error.id = res.id;
  }
  if (res.status) {
    error.status = res.status;
  }
  if (res.statusText) {
    error.name = res.statusText;
  }
  if (res.missing) {
    error.missing = res.missing;
  }

  return error;
};