'use strict';

// //////////////////////////////////////////////////////////////////////////////
// / DISCLAIMER
// /
// / Copyright 2016 ArangoDB GmbH, Cologne, Germany
// /
// / Licensed under the Apache License, Version 2.0 (the "License")
// / you may not use this file except in compliance with the License.
// / You may obtain a copy of the License at
// /
// /     http://www.apache.org/licenses/LICENSE-2.0
// /
// / Unless required by applicable law or agreed to in writing, software
// / distributed under the License is distributed on an "AS IS" BASIS,
// / WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// / See the License for the specific language governing permissions and
// / limitations under the License.
// /
// / Copyright holder is ArangoDB GmbH, Cologne, Germany
// /
// / @author Alan Plum
// //////////////////////////////////////////////////////////////////////////////

const _ = require('lodash');
const dd = require('dedent');
const il = require('@arangodb/util').inline;
const joi = require('joi');
const util = require('util');
const statuses = require('statuses');
const mimeTypes = require('mime-types');
const mediaTyper = require('media-typer');
const ArangoError = require('@arangodb').ArangoError;
const ERROR_BAD_PARAMETER = require('@arangodb').errors.ERROR_BAD_PARAMETER;

function normalizeMimeType (mime) {
  if (mime === 'binary') {
    mime = 'application/octet-stream';
  }
  const contentType = mimeTypes.contentType(mime) || mime;
  const parsed = mediaTyper.parse(contentType);
  return mediaTyper.format(_.pick(parsed, [
    'type',
    'subtype',
    'suffix'
  ]));
}

function findVariations (options) {
  const variants = [[]];
  for (let i = options.length - 1; i >= 0; i--) {
    const isOptional = options[i];
    const len = variants.length;
    if (isOptional) {
      for (let k = 0; k < len; k++) {
        variants.push([...variants[k]]);
      }
    }
    for (let k = 0; k < len; k++) {
      variants[k].unshift(i);
    }
  }
  return variants;
}

function runValidation (methodName, paramName, type, value) {
  const warnings = [];
  if (typeof type === 'string') {
    if (typeof value !== type) {
      return {
        value,
        error: new Error(`${paramName} must be a ${type}, not ${typeof value}`),
      warnings};
    }
    return {value, error: null, warnings};
  } else if (typeof type === 'function') {
    const result = type(value);
    if (result.warnings) {
      for (const warning of result.warnings) {
        warnings.push(warning.replace(/^"value"/, paramName));
      }
    }
    if (result.error) {
      result.error.message = result.error.message
        .replace(/^"value"/, paramName);
      return {value: result.value, error: result.error, warnings};
    }
    return {value: result.value, error: null, warnings};
  } else {
    throw new Error(il`
      Unknown type for parameter ${paramName} in ${methodName}:
      ${util.inspect(type)}
    `);
  }
}

module.exports = exports = function (methodName, paramNames, types, values) {
  const optionals = paramNames
    .map((paramName) => paramName.charAt(paramName.length - 1) === '?');
  paramNames = optionals.map((isOptional, i) => (
  isOptional ? paramNames[i].slice(0, -1) : paramNames[i]
  ));
  for (let i = values.length - 1; i >= 0; i--) {
    if (values[i] !== undefined) {
      break;
    }
    values.pop();
  }
  const validations = types.map(() => []);
  const warnings = [];
  let output;
  let error = null;
  for (const variation of findVariations(optionals)) {
    if (variation.length < values.length) {
      continue;
    }
    output = [];    let err = null;
    for (let i = 0; i < variation.length; i++) {
      const index = variation[i];
      const result = validations[i][index] || runValidation(
        methodName,
        paramNames[index],
        types[index],
        values[i]
      );
      for (const warning of result.warnings) {
        warnings.push(warning);
      }
      if (result.error) {
        err = result.error;
        break;
      }
      output[index] = result.value;
    }
    if (err) {
      error = err;
    } else {
      error = null;
      break;
    }
  }
  if (warnings.length || error) {
    const signature = optionals.map((isOptional, i) => (
    isOptional ? `[${paramNames[i]}]` : paramNames[i]
    )).join(', ');
    for (const warning of warnings) {
      console.warnLines(`${methodName}(${signature}): ${warning}`);
    }
    if (error) {
      throw Object.assign(
        new ArangoError({
          errorNum: ERROR_BAD_PARAMETER.code,
          errorMessage: dd`
            ${ERROR_BAD_PARAMETER.message}
            ${error.message}
            Method: ${methodName}(${signature})
            Arguments: ${util.inspect(values, {simpleJoi: true, depth: 3})}
          `
        }), {cause: error}
      );
    }
  }
  return output;
};

exports.validateMiddleware = function (value) {
  if (value && (typeof value === 'function' || typeof value.register === 'function')) {
    return {value, error: null};
  }
  return {value, error: new Error('"value" is not a valid middleware')};
};

exports.validateMountable = function (value) {
  if (value && value.isFoxxRouter) {
    return {value, error: null};
  }
  return exports.validateMiddleware(value);
};

exports.validateStatus = function (value) {
  let status = value;
  if (typeof status === 'string') {
    try {
      status = statuses(status);
    } catch (e) {
      return {value, error: Object.assign(
          new Error('"value" must be a valid status name.'),
          {cause: e}
      )};
    }
  }
  status = Number(status);
  if (Number.isNaN(status)) {
    return {value, error: new Error('"value" must be a number')};
  }
  return {value: status, error: null};
};

exports.validateSchema = function (value) {
  if (value) {
    if (value.isJoi || typeof value.validate === 'function') {
      return {value, error: null};
    }
    try {
      return {value: joi.object(value).required(), error: null};
    } catch (e) {
      return {value, error: Object.assign(
          new Error('"value" must be a schema'),
          {cause: e}
      )};
    }
  }
  return {value, error: new Error('"value" must be a schema.')};
};

exports.validateModel = function (value) {
  const warnings = [];
  let model = value;
  let multiple = false;
  if (model === null) {
    return {value: {model, multiple}, error: null};
  }
  if (Array.isArray(model)) {
    if (model.length !== 1) {
      return {value, error: new Error(il`
        "value" must be a model or schema
        or an array containing exactly one model or schema.
        If you are trying to use multiple schemas
        try using joi.alternatives instead.
      `), warnings};
    }
    model = model[0];
    multiple = true;
  }

  const index = multiple ? '[0]' : '';
  if (!model || typeof model !== 'object') {
    return {value, error: new Error(
        `"value"${index} is not an object`
    )};
  }

  const result = exports.validateSchema(model);
  if (!result.error) {
    model = {schema: result.value};
  }

  if (model.schema) {
    const result = exports.validateSchema(model.schema);
    if (result.error) {
      result.error.message = result.error.message
        .replace(/^"value"/, `"value"${index}.schema`);
      return {value, error: result.error};
    }
    model.schema = result.value;
  }
  if (!model.forClient && typeof model.toClient === 'function') {
    warnings.push(il`
      "value"${index} has unexpected "toClient" method.
      Did you mean "forClient"?
    `);
  }
  if (model.forClient && typeof model.forClient !== 'function') {
    return {value, error: new Error(il`
      "value"${index}.forClient must be a function,
      not ${typeof model.forClient}.
    `), warnings};
  }
  if (model.fromClient && typeof model.fromClient !== 'function') {
    return {value, error: new Error(il`
      "value"${index}.fromClient must be a function,
      not ${typeof model.fromClient}.
    `), warnings};
  }
  return {value: {model, multiple}, error: null};
};

exports.validateMimes = function (value) {
  if (!Array.isArray(value)) {
    return {value, error: new Error(`"value" must be an array.`)};
  }
  const mimes = [];
  for (let i = 0; i < value.length; i++) {
    try {
      mimes.push(normalizeMimeType(value[i]));
    } catch (e) {
      return {value, error: Object.assign(
          new Error(`"value"[${i}] must be a valid MIME type.`),
          {cause: e}
      )};
    }
  }
  return {value: mimes, error: null};
};