import {task} from 'gulp';
import {sync as glob} from 'glob';
import * as fs from 'fs';
import * as path from 'path';
import * as ts from 'typescript';
import {buildConfig} from 'material2-build-tools';
const {packagesDir} = buildConfig;

interface ExampleMetadata {
  component: string;
  sourcePath: string;
  id: string;
  title: string;
  additionalComponents: string[];
  additionalFiles: string[];
  selectorName: string[];
}

interface ParsedMetadata {
  primary: boolean;
  component: string;
  title: string;
  templateUrl: string;
}

interface ParsedMetadataResults {
  primaryComponent: ParsedMetadata;
  secondaryComponents: ParsedMetadata[];
}

/** Path to find the examples */
const examplesPath = path.join(packagesDir, 'material-examples');

/** Output path of the module that is being created */
const outputModuleFilename = path.join(examplesPath, 'example-module.ts');

/** Build ES module import statements for the examples. */
function buildImportsTemplate(metadata: ExampleMetadata): string {
  const components = metadata.additionalComponents.concat(metadata.component);

  // Create a relative path to the source file of the current example.
  // The relative path will be used inside of a TypeScript import statement.
  const relativeSrcPath = path
    .relative(examplesPath, metadata.sourcePath)
    .replace(/\\/g, '/')
    .replace('.ts', '');

  return `import {${components.join(',')}} from './${relativeSrcPath}';
`;
}

/**
 * Builds the examples metadata including title, component, etc.
 */
function buildExamplesTemplate(metadata: ExampleMetadata): string {
  // if no additional files or selectors were provided,
  // return null since we don't care about if these were not found
  const additionalFiles = metadata.additionalFiles.length ?
    JSON.stringify(metadata.additionalFiles) : 'null';

  const selectorName = metadata.selectorName.length ?
    `'${metadata.selectorName.join(', ')}'` : 'null';

  return `'${metadata.id}': {
    title: '${metadata.title}',
    component: ${metadata.component},
    additionalFiles: ${additionalFiles},
    selectorName: ${selectorName}
  },
  `;
}

/**
 * Build the list of components template
 */
function buildListTemplate(metadata: ExampleMetadata): string {
  const components = metadata.additionalComponents.concat(metadata.component);
  return `${components.join(',')},
  `;
}

/**
 * Builds the template for the examples module
 */
function generateExampleNgModule(extractedMetadata: ExampleMetadata[]): string {
  return `
/* tslint:disable */
/** DO NOT MANUALLY EDIT THIS FILE, IT IS GENERATED VIA GULP 'build-examples-module' */
import {NgModule} from '@angular/core';
import {FormsModule, ReactiveFormsModule} from '@angular/forms';
import {CommonModule} from '@angular/common';
import {ExampleMaterialModule} from './material-module';

export interface LiveExample {
  title: string;
  component: any;
  additionalFiles?: string[];
  selectorName?: string;
}

${extractedMetadata.map(r => buildImportsTemplate(r)).join('').trim()}

export const EXAMPLE_COMPONENTS = {
  ${extractedMetadata.map(r => buildExamplesTemplate(r)).join('').trim()}
};

export const EXAMPLE_LIST = [
  ${extractedMetadata.map(r => buildListTemplate(r)).join('').trim()}
];

@NgModule({
  declarations: EXAMPLE_LIST,
  entryComponents: EXAMPLE_LIST,
  imports: [
    ExampleMaterialModule,
    FormsModule,
    ReactiveFormsModule,
    CommonModule
  ]
})
export class ExampleModule { }
`;
}

/**
 * Given a string that is a camel or pascal case,
 * this function will convert to dash case.
 */
function convertToDashCase(name: string): string {
  name = name.replace(/[A-Z]/g, ' $&');
  name = name.toLowerCase().trim();
  return name.split(' ').join('-');
}

/**
 * Parse the AST of a file and get metadata about it
 */
function parseExampleMetadata(fileName: string, sourceContent: string): ParsedMetadataResults {
  const sourceFile = ts.createSourceFile(
    fileName, sourceContent, ts.ScriptTarget.Latest, false, ts.ScriptKind.TS);

  const metas: any[] = [];

  const visit = (node: any): void => {
    if (node.kind === ts.SyntaxKind.ClassDeclaration) {
      const meta: any = {
        component: node.name.text
      };

      if (node.jsDoc && node.jsDoc.length) {
        for (const doc of node.jsDoc) {
          if (doc.tags && doc.tags.length) {
            for (const tag of doc.tags) {
              const tagValue = tag.comment;
              const tagName = tag.tagName.text;
              if (tagName === 'title') {
                meta.title = tagValue;
                meta.primary = true;
              }
            }
          }
        }
      }

      if (node.decorators && node.decorators.length) {
        for (const decorator of node.decorators) {
          if (decorator.expression.expression.text === 'Component') {
            for (const arg of decorator.expression.arguments) {
              for (const prop of arg.properties) {
                const name = prop.name.text;
                const value = prop.initializer.text;
                meta[name] = value;
              }
            }

            metas.push(meta);
          }
        }
      }
    }

    ts.forEachChild(node, visit);
  };

  visit(sourceFile);

  return {
    primaryComponent: metas.find(m => m.primary),
    secondaryComponents: metas.filter(m => !m.primary)
  };
}

/**
 * Creates the examples module and metadata
 */
task('build-examples-module', () => {
  const results: ExampleMetadata[] = [];
  const matchedFiles = glob(path.join(examplesPath, '**/*.ts'));

  for (const sourcePath of matchedFiles) {
    const sourceContent = fs.readFileSync(sourcePath, 'utf-8');
    const { primaryComponent, secondaryComponents } =
      parseExampleMetadata(sourcePath, sourceContent);

    if (primaryComponent) {
      // Generate a unique id for the component by converting the class name to dash-case.
      const id = convertToDashCase(primaryComponent.component.replace('Example', ''));

      const example: ExampleMetadata = {
        sourcePath,
        id,
        component: primaryComponent.component,
        title: primaryComponent.title,
        additionalComponents: [],
        additionalFiles: [],
        selectorName: []
      };

      if (secondaryComponents.length) {
        example.selectorName.push(example.component);

        for (const meta of secondaryComponents) {
          example.additionalComponents.push(meta.component);
          example.additionalFiles.push(meta.templateUrl);
          example.selectorName.push(meta.component);
        }
      }

      results.push(example);
    }
  }

  const generatedModuleFile = generateExampleNgModule(results);
  fs.writeFileSync(outputModuleFilename, generatedModuleFile);
});