import * as ts from 'typescript';

import {Evaluator, ImportMetadata, ImportSpecifierMetadata} from './evaluator';
import {ClassMetadata, ConstructorMetadata, ModuleMetadata, MemberMetadata, MetadataMap, MetadataSymbolicExpression, MetadataSymbolicReferenceExpression, MetadataValue, MethodMetadata} from './schema';
import {Symbols} from './symbols';


/**
 * Collect decorator metadata from a TypeScript module.
 */
export class MetadataCollector {
  constructor() {}

  collectImports(sourceFile: ts.SourceFile) {
    let imports: ImportMetadata[] = [];
    const stripQuotes = (s: string) => s.replace(/^['"]|['"]$/g, '');
    function visit(node: ts.Node) {
      switch (node.kind) {
        case ts.SyntaxKind.ImportDeclaration:
          const importDecl = <ts.ImportDeclaration>node;
          const from = stripQuotes(importDecl.moduleSpecifier.getText());
          const newImport = {from};
          if (!importDecl.importClause) {
            // Bare imports do not bring symbols into scope, so we don't need to record them
            break;
          }
          if (importDecl.importClause.name) {
            (<any>newImport)['defaultName'] = importDecl.importClause.name.text;
          }
          const bindings = importDecl.importClause.namedBindings;
          if (bindings) {
            switch (bindings.kind) {
              case ts.SyntaxKind.NamedImports:
                const namedImports: ImportSpecifierMetadata[] = [];
                (<ts.NamedImports>bindings).elements.forEach(i => {
                  const namedImport = {name: i.name.text};
                  if (i.propertyName) {
                    (<any>namedImport)['propertyName'] = i.propertyName.text;
                  }
                  namedImports.push(namedImport);
                });
                (<any>newImport)['namedImports'] = namedImports;
                break;
              case ts.SyntaxKind.NamespaceImport:
                (<any>newImport)['namespace'] = (<ts.NamespaceImport>bindings).name.text;
                break;
            }
          }
          imports.push(newImport);
          break;
      }
      ts.forEachChild(node, visit);
    }
    ts.forEachChild(sourceFile, visit);
    return imports;
  }

  /**
   * Returns a JSON.stringify friendly form describing the decorators of the exported classes from
   * the source file that is expected to correspond to a module.
   */
  public getMetadata(sourceFile: ts.SourceFile, typeChecker: ts.TypeChecker): ModuleMetadata {
    const locals = new Symbols();
    const evaluator = new Evaluator(typeChecker, locals, this.collectImports(sourceFile));

    function objFromDecorator(decoratorNode: ts.Decorator): MetadataSymbolicExpression {
      return <MetadataSymbolicExpression>evaluator.evaluateNode(decoratorNode.expression);
    }

    function referenceFromType(type: ts.Type): MetadataSymbolicReferenceExpression {
      if (type) {
        let symbol = type.getSymbol();
        if (symbol) {
          return evaluator.symbolReference(symbol);
        }
      }
    }

    function classMetadataOf(classDeclaration: ts.ClassDeclaration): ClassMetadata {
      let result: ClassMetadata = {__symbolic: 'class'};

      function getDecorators(decorators: ts.Decorator[]): MetadataSymbolicExpression[] {
        if (decorators && decorators.length)
          return decorators.map(decorator => objFromDecorator(decorator));
        return undefined;
      }

      // Add class decorators
      if (classDeclaration.decorators) {
        result.decorators = getDecorators(classDeclaration.decorators);
      }

      // member decorators
      let members: MetadataMap = null;
      function recordMember(name: string, metadata: MemberMetadata) {
        if (!members) members = {};
        let data = members.hasOwnProperty(name) ? members[name] : [];
        data.push(metadata);
        members[name] = data;
      }
      for (const member of classDeclaration.members) {
        let isConstructor = false;
        switch (member.kind) {
          case ts.SyntaxKind.Constructor:
            isConstructor = true;
          // fallthrough
          case ts.SyntaxKind.MethodDeclaration:
            const method = <ts.MethodDeclaration|ts.ConstructorDeclaration>member;
            const methodDecorators = getDecorators(method.decorators);
            const parameters = method.parameters;
            const parameterDecoratorData: MetadataSymbolicExpression[][] = [];
            const parametersData: MetadataSymbolicReferenceExpression[] = [];
            let hasDecoratorData: boolean = false;
            let hasParameterData: boolean = false;
            for (const parameter of parameters) {
              const parameterData = getDecorators(parameter.decorators);
              parameterDecoratorData.push(parameterData);
              hasDecoratorData = hasDecoratorData || !!parameterData;
              if (isConstructor) {
                const parameterType = typeChecker.getTypeAtLocation(parameter);
                parametersData.push(referenceFromType(parameterType) || null);
                hasParameterData = true;
              }
            }
            const data: MethodMetadata = {__symbolic: isConstructor ? 'constructor' : 'method'};
            const name = isConstructor ? '__ctor__' : evaluator.nameOf(member.name);
            if (methodDecorators) {
              data.decorators = methodDecorators;
            }
            if (hasDecoratorData) {
              data.parameterDecorators = parameterDecoratorData;
            }
            if (hasParameterData) {
              (<ConstructorMetadata>data).parameters = parametersData;
            }
            recordMember(name, data);
            break;
          case ts.SyntaxKind.PropertyDeclaration:
          case ts.SyntaxKind.GetAccessor:
          case ts.SyntaxKind.SetAccessor:
            const property = <ts.PropertyDeclaration>member;
            const propertyDecorators = getDecorators(property.decorators);
            if (propertyDecorators) {
              recordMember(
                  evaluator.nameOf(property.name),
                  {__symbolic: 'property', decorators: propertyDecorators});
            }
            break;
        }
      }
      if (members) {
        result.members = members;
      }

      return result.decorators || members ? result : undefined;
    }

    let metadata: {[name: string]: (ClassMetadata | MetadataValue)};
    const symbols = typeChecker.getSymbolsInScope(sourceFile, ts.SymbolFlags.ExportValue);
    for (var symbol of symbols) {
      for (var declaration of symbol.getDeclarations()) {
        switch (declaration.kind) {
          case ts.SyntaxKind.ClassDeclaration:
            const classDeclaration = <ts.ClassDeclaration>declaration;
            if (classDeclaration.decorators) {
              if (!metadata) metadata = {};
              metadata[classDeclaration.name.text] = classMetadataOf(classDeclaration);
            }
            break;
          case ts.SyntaxKind.VariableDeclaration:
            const variableDeclaration = <ts.VariableDeclaration>declaration;
            if (variableDeclaration.initializer) {
              const value = evaluator.evaluateNode(variableDeclaration.initializer);
              if (value !== undefined) {
                if (evaluator.isFoldable(variableDeclaration.initializer)) {
                  // Record the value for use in other initializers
                  locals.set(symbol, value);
                }
                if (!metadata) metadata = {};
                metadata[evaluator.nameOf(variableDeclaration.name)] =
                    evaluator.evaluateNode(variableDeclaration.initializer);
              }
            }
            break;
        }
      }
    }

    return metadata && {__symbolic: 'module', metadata};
  }
}