const ts = require('typescript');
const path = require('path');
const Documentation = require('./Documentation');
module.exports = checkSources;


/**
 * @param {!Array<!import('../Source')>} sources
 */
function checkSources(sources) {
  // special treatment for Events.js
  const classEvents = new Map();
  const eventsSource = sources.find(source => source.name() === 'Events.js');
  if (eventsSource) {
    const {Events} = require(eventsSource.filePath());
    for (const [className, events] of Object.entries(Events))
      classEvents.set(className, Array.from(Object.values(events)).filter(e => typeof e === 'string').map(e => Documentation.Member.createEvent(e)));
  }

  const excludeClasses = new Set([]);
  const program = ts.createProgram({
    options: {
      allowJs: true,
      target: ts.ScriptTarget.ES2017
    },
    rootNames: sources.map(source => source.filePath())
  });
  const checker = program.getTypeChecker();
  const sourceFiles = program.getSourceFiles();
  /** @type {!Array<!Documentation.Class>} */
  const classes = [];
  /** @type {!Map<string, string>} */
  const inheritance = new Map();

  const sourceFilesNoNodeModules = sourceFiles.filter(x => !x.fileName.includes('node_modules'));
  const sourceFileNamesSet = new Set(sourceFilesNoNodeModules.map(x => x.fileName));
  sourceFilesNoNodeModules.map(x => {
    if (x.fileName.includes('/lib/')) {
      const potentialTSSource = x.fileName.replace('lib', 'src').replace('.js', '.ts');
      if (sourceFileNamesSet.has(potentialTSSource)) {
        /* Not going to visit this file because we have the TypeScript src code
         * which we'll use instead.
         */
        return;
      }
    }

    visit(x);
  });

  const errors = [];
  const documentation = new Documentation(recreateClassesWithInheritance(classes, inheritance));

  return {errors, documentation};

  /**
   * @param {!Array<!Documentation.Class>} classes
   * @param {!Map<string, string>} inheritance
   * @return {!Array<!Documentation.Class>}
   */
  function recreateClassesWithInheritance(classes, inheritance) {
    const classesByName = new Map(classes.map(cls => [cls.name, cls]));
    return classes.map(cls => {
      const membersMap = new Map();
      for (let wp = cls; wp; wp = classesByName.get(inheritance.get(wp.name))) {
        for (const member of wp.membersArray) {
          // Member was overridden.
          const memberId = member.kind + ':' + member.name;
          if (membersMap.has(memberId))
            continue;
          membersMap.set(memberId, member);
        }
      }
      return new Documentation.Class(cls.name, Array.from(membersMap.values()));
    });
  }


  /**
   * @param {!ts.Node} node
   */
  function visit(node) {
    if (ts.isClassDeclaration(node) || ts.isClassExpression(node)) {
      const symbol = node.name ? checker.getSymbolAtLocation(node.name) : node.symbol;
      let className = symbol.getName();

      if (className === '__class') {
        let parent = node;
        while (parent.parent)
          parent = parent.parent;
        className = path.basename(parent.fileName,  '.js');
      }
      if (className && !excludeClasses.has(className)) {
        classes.push(serializeClass(className, symbol, node));
        const parentClassName = parentClass(node);
        if (parentClassName)
          inheritance.set(className, parentClassName);
        excludeClasses.add(className);
      }
    }
    ts.forEachChild(node, visit);
  }

  function parentClass(classNode) {
    for (const herigateClause of classNode.heritageClauses || []) {
      for (const heritageType of herigateClause.types) {
        const parentClassName = heritageType.expression.escapedText;
        return parentClassName;
      }
    }
    return null;

  }

  function serializeSymbol(symbol, circular = []) {
    const type = checker.getTypeOfSymbolAtLocation(symbol, symbol.valueDeclaration);
    const name = symbol.getName();
    if (symbol.valueDeclaration && symbol.valueDeclaration.dotDotDotToken) {
      const innerType = serializeType(type.typeArguments[0], circular);
      innerType.name = '...' + innerType.name;
      return Documentation.Member.createProperty('...' + name, innerType);
    }
    return Documentation.Member.createProperty(name, serializeType(type, circular));
  }

  /**
   * @param {!ts.ObjectType} type
   */
  function isRegularObject(type) {
    if (type.isIntersection())
      return true;
    if (!type.objectFlags)
      return false;
    if (!('aliasSymbol' in type))
      return false;
    if (type.getConstructSignatures().length)
      return false;
    if (type.getCallSignatures().length)
      return false;
    if (type.isLiteral())
      return false;
    if (type.isUnion())
      return false;


    return true;
  }

  /**
   * @param {!ts.Type} type
   * @return {!Documentation.Type}
   */
  function serializeType(type, circular = []) {
    let typeName = checker.typeToString(type);
    if (typeName === 'any' || typeName === '{ [x: string]: string; }' || typeName === '{}')
      typeName = 'Object';
    const nextCircular = [typeName].concat(circular);

    if (isRegularObject(type)) {
      let properties = undefined;
      if (!circular.includes(typeName))
        properties = type.getProperties().map(property => serializeSymbol(property, nextCircular));
      return new Documentation.Type('Object', properties);
    }
    if (type.isUnion() && typeName.includes('|')) {
      const types = type.types.map(type => serializeType(type, circular));
      const name = types.map(type => type.name).join('|');
      const properties = [].concat(...types.map(type => type.properties));
      return new Documentation.Type(name.replace(/false\|true/g, 'boolean'), properties);
    }
    if (type.typeArguments) {
      const properties = [];
      const innerTypeNames = [];
      for (const typeArgument of type.typeArguments) {
        const innerType = serializeType(typeArgument, nextCircular);
        if (innerType.properties)
          properties.push(...innerType.properties);
        innerTypeNames.push(innerType.name);
      }
      if (innerTypeNames.length === 0 || innerTypeNames.length === 1 && innerTypeNames[0] === 'void')
        return new Documentation.Type(type.symbol.name);
      return new Documentation.Type(`${type.symbol.name}<${innerTypeNames.join(', ')}>`, properties);
    }
    return new Documentation.Type(typeName, []);
  }

  /**
   * @param {!ts.Symbol} symbol
   * @return {boolean}
   */
  function symbolHasPrivateModifier(symbol) {
    const modifiers = symbol.valueDeclaration.modifiers || [];
    return modifiers.some(modifier => modifier.kind === ts.SyntaxKind.PrivateKeyword);
  }

  /**
   * @param {string} className
   * @param {!ts.Symbol} symbol
   * @return {}
   */
  function serializeClass(className, symbol, node) {
    /** @type {!Array<!Documentation.Member>} */
    const members = classEvents.get(className) || [];

    for (const [name, member] of symbol.members || []) {

      /* Before TypeScript we denoted private methods with an underscore
       * but in TypeScript we use the private keyword
       * hence we check for either here.
       */
      if (name.startsWith('_') || symbolHasPrivateModifier(member))
        continue;

      const memberType = checker.getTypeOfSymbolAtLocation(member, member.valueDeclaration);
      const signature = memberType.getCallSignatures()[0];
      if (signature)
        members.push(serializeSignature(name, signature));
      else
        members.push(serializeProperty(name, memberType));
    }

    return new Documentation.Class(className, members);
  }

  /**
   * @param {string} name
   * @param {!ts.Signature} signature
   */
  function serializeSignature(name, signature) {
    const parameters = signature.parameters.map(s => serializeSymbol(s));
    const returnType = serializeType(signature.getReturnType());
    return Documentation.Member.createMethod(name, parameters, returnType.name !== 'void' ? returnType : null);
  }

  /**
   * @param {string} name
   * @param {!ts.Type} type
   */
  function serializeProperty(name, type) {
    return Documentation.Member.createProperty(name, serializeType(type));
  }
}