/**
 * Copyright (c) Microsoft Corporation.
 *
 * 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.
 */

// @ts-check

const path = require('path');
const Documentation = require('./documentation');
const XmlDoc = require('./xmlDocumentation')
const PROJECT_DIR = path.join(__dirname, '..', '..');
const fs = require('fs');
const { parseApi } = require('./api_parser');
const { Type } = require('./documentation');
const { args } = require('commander');
const { EOL } = require('os');

const maxDocumentationColumnWidth = 80;

/** @type {Map<string, Documentation.Type>} */
const additionalTypes = new Map(); // this will hold types that we discover, because of .NET specifics, like results
/** @type {Map<string, string>} */
const documentedResults = new Map(); // will hold documentation for new types
/** @type {Map<string, string[]>} */
const enumTypes = new Map();

let documentation;
/** @type {Map<string, string>} */
let classNameMap;

{
  const typesDir = process.argv[2] || '../generate_types/csharp/';
  let checkAndMakeDir = (path) => {
    if (!fs.existsSync(path))
      fs.mkdirSync(path, { recursive: true });
  };

  const modelsDir = path.join(typesDir, "models");
  const enumsDir = path.join(typesDir, "enums");

  checkAndMakeDir(typesDir);
  checkAndMakeDir(modelsDir);
  checkAndMakeDir(enumsDir);

  documentation = parseApi(path.join(PROJECT_DIR, 'docs', 'src', 'api'));
  documentation.filterForLanguage('csharp');

  documentation.setLinkRenderer(item => {
    if (item.clazz)
      return `<see cref="${translateMemberName("interface", item.clazz.name, null)}"/>`;
    else if (item.member)
      return `<see cref="${translateMemberName("interface", item.member.clazz.name, null)}.${translateMemberName(item.member.kind, item.member.name, item.member)}"/>`;
    else if (item.option)
      return `<paramref name="${item.option}"/>`;
    else if (item.param)
      return `<paramref name="${item.param}"/>`;
    else
      throw new Error('Unknown link format.');
  });

  // get the template for a class
  const template = fs.readFileSync("./templates/interface.cs", 'utf-8')
    .replace('[PW_TOOL_VERSION]', `${__filename.substring(path.join(__dirname, '..', '..').length).split(path.sep).join(path.posix.sep)}`);

  // we have some "predefined" types, like the mixed state enum, that we can map in advance
  enumTypes.set("MixedState", ["On", "Off", "Mixed"]);

  // map the name to a C# friendly one (we prepend an I to denote an interface)
  classNameMap = new Map(documentation.classesArray.map(x => [x.name, translateMemberName('interface', x.name, null)]));

  // map some types that we know of
  classNameMap.set('Error', 'Exception');
  classNameMap.set('TimeoutError', 'TimeoutException');
  classNameMap.set('EvaluationArgument', 'object');
  classNameMap.set('boolean', 'bool');
  classNameMap.set('Serializable', 'T');
  classNameMap.set('any', 'object');
  classNameMap.set('Buffer', 'byte[]');
  classNameMap.set('path', 'string');
  classNameMap.set('URL', 'string');
  classNameMap.set('RegExp', 'Regex');

  // this are types that we don't explicility render even if we get the specs
  const ignoredTypes = ['TimeoutException'];

  let writeFile = (name, out, folder) => {
    let content = template.replace('[CONTENT]', out.join(`${EOL}\t`));
    fs.writeFileSync(`${path.join(folder, name)}.generated.cs`, content);
  }

  /**
   * 
   * @param {string} kind 
   * @param {string} name 
   * @param {Documentation.MarkdownNode[]} spec
   * @param {function(string[]): void} callback 
   * @param {string} folder
   * @param {string} extendsName
   */
  let innerRenderElement = (kind, name, spec, callback, folder = typesDir, extendsName = null) => {
    const out = [];
    console.log(`Generating ${name}`);

    if (spec)
      out.push(...XmlDoc.renderXmlDoc(spec, maxDocumentationColumnWidth));
    else {
      let ownDocumentation = documentedResults.get(name);
      if (ownDocumentation) {
        out.push('/// <summary>');
        out.push(`/// ${ownDocumentation}`);
        out.push('/// </summary>');
      }
    }

    if (extendsName === 'IEventEmitter')
      extendsName = null;

    out.push(`public ${kind} ${name}${extendsName ? ` : ${extendsName}` : ''}`);
    out.push('{');

    callback(out);

    // we want to separate the items with a space and this is nicer, than holding 
    // an index in each iterator down the line
    const lastLine = out.pop();
    if (lastLine !== '')
      out.push(lastLine);

    out.push('}');

    writeFile(name, out, folder);
  };

  for (const element of documentation.classesArray) {
    const name = classNameMap.get(element.name);
    if (ignoredTypes.includes(name))
      continue;

    innerRenderElement('partial interface', name, element.spec, (out) => {
      for (const member of element.membersArray) {
        renderMember(member, element, out);
      }
    }, typesDir, translateMemberName('interface', element.extends, null));
  }

  additionalTypes.forEach((type, name) =>
    innerRenderElement('partial class', name, null, (out) => {
      // TODO: consider how this could be merged with the `translateType` check
      if (type.union
        && type.union[0].name === 'null'
        && type.union.length == 2) {
        type = type.union[1];
      }

      if (type.name === 'Array') {
        throw new Error('Array at this stage is unexpected.');
      } else if (type.properties) {
        for (const member of type.properties) {
          let fakeType = new Type(name, null);
          renderMember(member, fakeType, out);
        }
      } else {
        console.log(type);
        throw new Error(`Not sure what to do in this case.`);
      }
    }, modelsDir));

  enumTypes.forEach((values, name) =>
    innerRenderElement('enum', name, null, (out) => {
      out.push('\tUndefined = 0,');
      values.forEach((v, i) => {
        // strip out the quotes
        v = v.replace(/[\"]/g, ``)
        let escapedName = v.replace(/[-]/g, ' ')
          .split(' ')
          .map(word => word[0].toUpperCase() + word.substring(1)).join('');

        out.push(`\t[EnumMember(Value = "${v}")]`);
        out.push(`\t${escapedName},`);
      });
    }, enumsDir));
}

/**
 * @param {string} memberKind  
 * @param {string} name 
 * @param {Documentation.Member} member 
 */
function translateMemberName(memberKind, name, member = null) {
  if (!name) return name;

  // we strip it for special chars, like @ because we might get called back with it in some special cases
  // like, when generating classes inside methods for params
  name = name.replace(/[@-]/g, '');

  if (memberKind === 'argument') {
    if (['params', 'event'].includes(name)) { // just in case we want to add others
      return `@${name}`;
    } else {
      return name;
    }
  }

  // check if there's an alias in the docs, in which case
  // we return that, otherwise, we apply our dotnet magic to it
  if (member) {
    if (member.alias !== name) {
      return member.alias;
    }
  }

  // we sanitize some common abbreviations to ensure consistency
  name = name.replace(/(HTTP[S]?)/g, (m, g) => {
    return g[0].toUpperCase() + g.substring(1).toLowerCase();
  });

  let assumedName = name.charAt(0).toUpperCase() + name.substring(1);

  switch (memberKind) {
    case "interface":
      // apply name mapping if the map exists
      let mappedName = classNameMap ? classNameMap.get(assumedName) : null;
      if (mappedName)
        return mappedName;
      return `I${assumedName}`;
    case "method":
      if (member && member.async)
        return `${assumedName}Async`;
      return assumedName;
    case "event":
      return `${assumedName}`;
    case "enum":
      return `${assumedName}`;
    default:
      return `${assumedName}`;
  }
}

/**
 * 
 * @param {Documentation.Member} member 
 * @param {Documentation.Class|Documentation.Type} parent 
 * @param {string[]} out
 */
function renderMember(member, parent, out) {
  let output = line => {
    if (typeof (line) === 'string')
      out.push(`\t${line}`);
    else
      out.push(...line.map(x => `\t${x}`));
  }

  let name = translateMemberName(member.kind, member.name, member);
  if (member.kind === 'method') {
    renderMethod(member, parent, output, name);
  } else {
    let type = translateType(member.type, parent, t => generateNameDefault(member, name, t, parent));
    if (member.kind === 'event') {
      if (!member.type)
        throw new Error(`No Event Type for ${name} in ${parent.name}`);
      if (member.spec)
        output(XmlDoc.renderXmlDoc(member.spec, maxDocumentationColumnWidth));
      if (parent && (classNameMap.get(parent.name) === type))
        output(`event EventHandler ${name};`); // event sender will be the type, so we're fine to ignore
      else
        output(`event EventHandler<${type}> ${name};`);
    } else if (member.kind === 'property') {
      if (member.spec)
        output(XmlDoc.renderXmlDoc(member.spec, maxDocumentationColumnWidth));
      let propertyOrigin = member.name;
      if (member.type.expression === '[string]|[float]')
        propertyOrigin = `${member.name}String`;
      output(`[JsonPropertyName("${propertyOrigin}")]`)
      if (parent && member && member.name === 'children') {  // this is a special hack for Accessibility
        console.warn(`children property found in ${parent.name}, assuming array.`);
        type = `IEnumerable<${parent.name}>`;
      }
      output(`public ${type} ${name} { get; set; }`);
    } else {
      throw new Error(`Problem rendering a member: ${type} - ${name} (${member.kind})`);
    }
  }

  // we're separating each entry and removing the final blank line when rendering
  out.push('');
}

/**
 * 
 * @param {Documentation.Member} member 
 * @param {string} name 
 * @param {Documentation.Type} t 
 * @param {*} parent 
 */
function generateNameDefault(member, name, t, parent) {
  if (!t.properties
    && !t.templates
    && !t.union
    && t.expression === '[Object]')
    return 'object';

  // we'd get this call for enums, primarily
  let enumName = generateEnumNameIfApplicable(member, name, t, parent);
  if (!enumName && member) {
    if (member.kind === 'method' || member.kind === 'property') {
      // this should be easy to name... let's call it the same as the argument (eternal optimist)
      let probableName = `${parent.name}${translateMemberName(``, name, null)}`;
      let probableType = additionalTypes.get(probableName);
      if (probableType) {
        // compare it with what?
        if (probableType.expression != t.expression) {
          throw new Error(`Non-matching types with the same name. Panic.`);
        }
      } else {
        additionalTypes.set(probableName, t);
      }

      return probableName;
    }

    if (member.kind === 'event') {
      return `${name}Payload`;
    }
  }

  return enumName || t.name;
}

function generateEnumNameIfApplicable(member, name, type, parent) {
  if (!type.union)
    return null;

  const potentialValues = type.union.filter(u => u.name.startsWith('"'));
  if ((potentialValues.length !== type.union.length)
    && !(type.union[0].name === 'null' && potentialValues.length === type.union.length - 1))
    return null; // this isn't an enum, so we don't care, we let the caller generate the name

  if (type && type.name)
    return type.name;

  // our enum naming policy leaves a few bits to be desired, but it'll do for now
  // however, with the recent changes, this almost never gets called anymore
  return translateMemberName('enum', name, type);
}

/**
 * Rendering a method is so _special_, with so many weird edge cases, that it
 * makes sense to put it separate from the other logic. 
 * @param {Documentation.Member} member 
 * @param {Documentation.Class|Documentation.Type} parent 
 * @param {Function} output
 */
function renderMethod(member, parent, output, name) {
  const typeResolve = (type) => translateType(type, parent, (t) => {
    let newName = `${parent.name}${translateMemberName(member.kind, member.name, null)}Result`;
    documentedResults.set(newName, `Result of calling <see cref="${translateMemberName("interface", parent.name)}.${translateMemberName(member.kind, member.name, member)}"/>.`);
    return newName;
  });

  /** @type {Map<string, string[]>} */
  const paramDocs = new Map();
  const addParamsDoc = (paramName, docs) => {
    if (paramName.startsWith('@'))
      paramName = paramName.substring(1);
    if (paramDocs.get(paramName))
      throw new Error(`Parameter ${paramName} already exists in the docs.`);
    paramDocs.set(paramName, docs);
  };

  /** @type {string} */
  let type = null;
  // need to check the original one
  if (member.type.name === 'Object' || member.type.name === 'Array') {
    let innerType = member.type;
    let isArray = false;
    if (innerType.name === 'Array') {
      // we want to influence the name, but also change the object type
      innerType = member.type.templates[0];
      isArray = true;
    }

    if (innerType.expression === '[Object]<[string], [string]>') {
      // do nothing, because this is handled down the road
    } else if (!isArray && !innerType.properties) {
      type = `dynamic`;
    } else {
      type = classNameMap.get(innerType.name);
      if (!type) {
        type = typeResolve(innerType);
      }

      if (isArray)
        type = `IReadOnlyCollection<${type}>`;
    }
  }

  type = type || typeResolve(member.type);
  // TODO: this is something that will probably go into the docs
  // translate simple getters into read-only properties, and simple
  // set-only methods to settable properties
  if (member.args.size == 0
    && type !== 'void'
    && !name.startsWith('Get')) {
    if (!member.async) {
      if (member.spec)
        output(XmlDoc.renderXmlDoc(member.spec, maxDocumentationColumnWidth));
      output(`${type} ${name} { get; }`);
      return;
    }
    name = `Get${name}`;
  } else if (member.args.size == 1
    && type === 'void'
    && name.startsWith('Set')
    && !member.async) {
    name = name.substring(3); // remove the 'Set'
    if (member.spec)
      output(XmlDoc.renderXmlDoc(member.spec, maxDocumentationColumnWidth));
    output(`${translateType(member.argsArray[0].type, parent)} ${name} { set; }`);
    return;
  }

  // HACK: special case for generics handling!
  if (type === 'T') {
    name = `${name}<T>`;
  }

  // adjust the return type for async methods
  if (member.async) {
    if (type === 'void')
      type = `Task`;
    else
      type = `Task<${type}>`;
  }

  // render args
  let args = [];
  /**
   * 
   * @param {string} innerArgType 
   * @param {string} innerArgName 
   * @param {Documentation.Member} argument 
   */
  const pushArg = (innerArgType, innerArgName, argument) => {
    let isEnum = enumTypes.has(innerArgType);
    let isNullable = ['int', 'bool', 'decimal', 'float'].includes(innerArgType);
    const requiredPrefix = argument.required ? "" : isNullable ? "?" : "";
    const requiredSuffix = argument.required ? "" : " = default";
    args.push(`${innerArgType}${requiredPrefix} ${innerArgName}${requiredSuffix}`);
  };

  let parseArg = (/** @type {Documentation.Member} */ arg) => {
    if (arg.name === "options") {
      arg.type.properties.forEach(prop => {
        parseArg(prop);
      });
      return;
    }

    if (arg.type.expression === '[string]|[path]') {
      let argName = translateMemberName('argument', arg.name, null);
      pushArg("string", `${argName} = null`, arg);
      pushArg("string", `${argName}Path = null`, arg);
      if (arg.spec) {
        addParamsDoc(argName, XmlDoc.renderTextOnly(arg.spec, maxDocumentationColumnWidth));
        addParamsDoc(`${argName}Path`, [`Instead of specifying <paramref name="${argName}"/>, gives the file name to load from.`]);
      }
      return;
    } else if (arg.type.expression === '[boolean]|[Array]<[string]>') {
      // HACK: this hurts my brain too
      // we split this into two args, one boolean, with the logical name
      let argName = translateMemberName('argument', arg.name, null);
      let leftArgType = translateType(arg.type.union[0], parent, (t) => { throw new Error('Not supported'); });
      let rightArgType = translateType(arg.type.union[1], parent, (t) => { throw new Error('Not supported'); });

      pushArg(leftArgType, argName, arg);
      pushArg(rightArgType, `${argName}Values`, arg);

      addParamsDoc(argName, XmlDoc.renderTextOnly(arg.spec, maxDocumentationColumnWidth));
      addParamsDoc(`${argName}Values`, [`The values to take into account when <paramref name="${argName}"/> is <code>true</code>.`]);

      return;
    }

    const argName = translateMemberName('argument', arg.alias || arg.name, null);
    const argType = translateType(arg.type, parent, (t) => generateNameDefault(member, argName, t, parent));

    if (argType === null && arg.type.union) {
      // we might have to split this into multiple arguments
      let translatedArguments = arg.type.union.map(t => translateType(t, parent, (x) => generateNameDefault(member, argName, x, parent)));
      if (translatedArguments.includes(null))
        throw new Error('Unexpected null in translated argument types. Aborting.');

      let argDocumentation = XmlDoc.renderTextOnly(arg.spec, maxDocumentationColumnWidth);
      for (const newArg of translatedArguments) {
        const sanitizedArgName = newArg.match(/(?<=^[\s"']*)(\w+)/g, '')[0] || newArg;
        const newArgName = `${argName}${sanitizedArgName[0].toUpperCase() + sanitizedArgName.substring(1)}`;
        pushArg(newArg, newArgName, arg);
        addParamsDoc(newArgName, argDocumentation);
      }
      return;
    }

    addParamsDoc(argName, XmlDoc.renderTextOnly(arg.spec, maxDocumentationColumnWidth));

    if (argName === 'timeout' && argType === 'decimal') {
      args.push(`int timeout = 0`); // a special argument, we ignore our convention
      return;
    }

    pushArg(argType, argName, arg);
  };

  member.argsArray
    .sort((a, b) =>  b.alias === 'options' ? -1 : 0) //move options to the back to the arguments list
    .forEach(parseArg);

  output(XmlDoc.renderXmlDoc(member.spec, maxDocumentationColumnWidth));
  paramDocs.forEach((val, ind) => {
    if (val && val.length === 1)
      output(`/// <param name="${ind}">${val}</param>`);
    else {
      output(`/// <param name="${ind}">`);
      output(val.map(l => `/// ${l}`));
      output(`/// </param>`);
    }
  });
  output(`${type} ${name}(${args.join(', ')});`);
}

/**
 * 
 *  @callback generateNameCallback
 *  @param {Documentation.Type} t
 *  @returns {string}
 */

/**
 *  @param {Documentation.Type} type 
 *  @param {Documentation.Class|Documentation.Type} parent
 *  @param {generateNameCallback} generateNameCallback
*/
function translateType(type, parent, generateNameCallback = t => t.name) {
  // a few special cases we can fix automatically
  if (type.expression === '[null]|[Error]')
    return 'void';
  else if (type.expression === '[boolean]|"mixed"')
    return 'MixedState';

  let isNullableEnum = false;
  if (type.union) {
    if (type.union[0].name === 'null') {
      // for dotnet, this is a nullable type
      // if the other side is a primitive type
      if (type.union.length > 2) {
        if (type.union.filter(x => x.name.startsWith('"')).length == type.union.length - 1)
          isNullableEnum = true;
        else
          throw new Error(`Union (${parent.name}) with null is too long.`);
      } else {
        const innerTypeName = translateType(type.union[1], parent, generateNameCallback);
        // if type is primitive, or an enum, then it's nullable
        if (innerTypeName === 'bool'
          || innerTypeName === 'int') {
          return `${innerTypeName}?`;
        }

        // if it's not a value type, it'll be nullable by default, so we can ignore it
        return `${innerTypeName}`;
      }
    }

    if (type.union.filter(u => u.name.startsWith(`"`)).length == type.union.length
      || isNullableEnum) {
      // this is an enum
      let enumName = generateNameCallback(type);
      if (!enumName)
        throw new Error(`This was supposed to be an enum, but it failed generating a name, ${type.name} ${parent ? parent.name : ""}.`);

      // make sure we map the enum, or invalidate the name, in case it doesn't match well
      const potentialEnum = enumTypes.get(enumName);
      let enumValues = type.union.filter(x => x.name !== 'null').map(x => x.name);
      if (potentialEnum) {
        // compare values
        if (potentialEnum.join(',') !== enumValues.join(',')) {
          // for now, we'll merge the two enums, if they have the same name, and we'll go from there
          potentialEnum.concat(enumValues.filter(x => !potentialEnum.includes(x))); // merge & de-dupe
          // TODO: think about doing global type annotation, where we can add comments, such as this?
          enumTypes.set(enumName, potentialEnum);
        }
      } else {
        enumTypes.set(enumName, enumValues);
      }
      if (isNullableEnum)
        return `${enumName}?`;
      return enumName;
    }

    if (type.expression === '[string]|[Buffer]')
      return `byte[]`; // TODO: make sure we implement extension methods for this!
    else if (type.expression === '[string]|[float]'
      || type.expression === '[string]|[float]|[boolean]') {
      console.warn(`${type.name} should be a 'string', but was a ${type.expression}`);
      return `string`;
    } else if (type.union.length == 2 && type.union[1].name === 'Array' && type.union[1].templates[0].name === type.union[0].name)
      return `IEnumerable<${type.union[0].name}>`; // an example of this is [string]|[Array]<[string]>
    else if (type.union[0].name === 'path')
      // we don't support path, but we know it's usually an object on the other end, and we expect
      // the dotnet folks to use [NameOfTheObject].LoadFromPath(); method which we can provide separately
      return translateType(type.union[1], parent, generateNameCallback);
    else if (type.expression === '[float]|"raf"')
      return `Polling`; // hardcoded because there's no other way to denote this

    return null;
  }

  if (type.name === 'Array') {
    if (type.templates.length != 1)
      throw new Error(`Array (${type.name} from ${parent.name}) has more than 1 dimension. Panic.`);

    let innerType = translateType(type.templates[0], parent, generateNameCallback);
    return `IEnumerable<${innerType}>`;
  }

  if (type.name === 'Object') {
    // take care of some common cases
    // TODO: this can be genericized
    if (type.templates && type.templates.length == 2) {
      // get the inner types of both templates, and if they're strings, it's a keyvaluepair string, string, 
      let keyType = translateType(type.templates[0], parent, generateNameCallback);
      let valueType = translateType(type.templates[1], parent, generateNameCallback);
      return `IEnumerable<KeyValuePair<${keyType}, ${valueType}>>`;
    }

    if ((type.name === 'Object')
      && !type.properties
      && !type.union) {
      return 'object';
    }
    // this is an additional type that we need to generate
    let objectName = generateNameCallback(type);
    if (objectName === 'Object') {
      throw new Error('Object unexpected');
    } else if (type.name === 'Object') {
      registerAdditionalType(objectName, type);
    }
    return objectName;
  }

  if (type.name === 'Map') {
    if (type.templates && type.templates.length == 2) {
      // we map to a dictionary
      let keyType = translateType(type.templates[0], parent, generateNameCallback);
      let valueType = translateType(type.templates[1], parent, generateNameCallback);
      return `Dictionary<${keyType}, ${valueType}>`;
    } else {
      throw 'Map has invalid number of templates.';
    }
  }

  if (type.name === 'function') {
    if (type.expression === '[function]' || !type.args)
      return 'Action'; // super simple mapping

    let argsList = '';
    if (type.args) {
      let translatedCallbackArguments = type.args.map(t => translateType(t, parent, generateNameCallback));
      if (translatedCallbackArguments.includes(null))
        throw new Error('There was an argument we could not parse. Aborting.');

      argsList = translatedCallbackArguments.join(', ');
    }

    if (!type.returnType) {
      // this is an Action
      return `Action<${argsList}>`;
    } else {
      let returnType = translateType(type.returnType, parent, generateNameCallback);
      if (returnType == null)
        throw new Error('Unexpected null as return type.');

      return `Func<${argsList}, ${returnType}>`;
    }
  }

  if (type.templates) {
    // this should mean we have a generic type and we can translate that
    /** @type {string[]} */
    var types = type.templates.map(template => translateType(template, parent));
    return `${type.name}<${types.join(', ')}>`
  }

  // there's a chance this is a name we've already seen before, so check
  // this is also where we map known types, like boolean -> bool, etc.
  let name = classNameMap.get(type.name) || type.name;
  return `${name}`;
}

/**
 * 
 * @param {string} typeName 
 * @param {Documentation.Type} type 
 */
function registerAdditionalType(typeName, type) {
  if (['object', 'string', 'int'].includes(typeName))
    return;

  let potentialType = additionalTypes.get(typeName);
  if (potentialType) {
    console.log(`Type ${typeName} already exists, so skipping...`);
    return;
  }

  additionalTypes.set(typeName, type);
}