import fs from 'fs';
import klawSync from 'klaw-sync';
import path from 'path';
import ts from 'typescript';

// tslint:disable:no-console
interface MemberInfo {
    name: string;
    description: string;
    type: string;
    defaultValue: string;
}

interface InterfaceInfo {
    title: string;
    weight: number;
    category: string;
    description: string;
    fileName: string;
    members: MemberInfo[];
}

const docsPath = '/docs/api/';
const outputPath = path.join(__dirname, '../docs/content/docs/api');
const vendureConfig = path.join(__dirname, '../server/src/config/vendure-config.ts');

deleteGeneratedDocs();
generateDocs();
console.log(`Watching for changes to ${vendureConfig}`);
fs.watchFile(vendureConfig, { interval: 1000 }, () => {
    generateDocs();
});

/**
 * Delete all generated docs found in the outputPath.
 */
function deleteGeneratedDocs() {
    let deleteCount = 0;
    const files = klawSync(outputPath, { nodir: true });
    for (const file of files) {
        const content = fs.readFileSync(file.path, 'utf-8');
        if (isGenerated(content)) {
            fs.unlinkSync(file.path);
            deleteCount ++;
        }
    }
    console.log(`Deleted ${deleteCount} generated docs`);
}

function isGenerated(content: string) {
    return /generated\: true\n---\n/.test(content);
}

function generateDocs() {
    const timeStart = +new Date();
    const sourceFile = ts.createSourceFile(
        vendureConfig,
        fs.readFileSync(vendureConfig).toString(),
        ts.ScriptTarget.ES2015,
        true,
    );
    const knownTypeMap = new Map<string, string>();

    const interfaces = [...sourceFile.statements]
        .filter(ts.isInterfaceDeclaration)
        .map(statement => {
            const info = parseInterface(statement);
            knownTypeMap.set(info.title, info.category + '/' + info.fileName);
            return info;
        });

    for (const info of interfaces) {
        const markdown = renderInterface(info, knownTypeMap);
        fs.writeFileSync(path.join(outputPath, info.category, info.fileName + '.md'), markdown);
    }

    console.log(`Generated ${interfaces.length} docs in ${+new Date() - timeStart}ms`);
}

/**
 * Parses an InterfaceDeclaration into a simple object which can be rendered into markdown.
 */
function parseInterface(statement: ts.InterfaceDeclaration): InterfaceInfo {
    const title = statement.name.text;
    const weight = getInterfaceWeight(statement);
    const category = getDocsCategory(statement);
    const description = getInterfaceDescription(statement);
    const fileName = title.split(/(?=[A-Z])/).join('-').toLowerCase();
    const members = parseMembers(statement.members);
    return {
        title,
        weight,
        category,
        description,
        fileName,
        members,
    };
}

/**
 * Parses an array of inteface members into a simple object which can be rendered into markdown.
 */
function parseMembers(members: ts.NodeArray<ts.TypeElement>): MemberInfo[] {
    const result: MemberInfo[] = [];

    for (const member of members) {
        if (ts.isPropertySignature(member)) {
            const name = member.name.getText();
            let description = '';
            let type = '';
            let defaultValue = '';
            parseTags(member, {
                description: tag => description += tag.comment || '',
                example: tag => description += formatExampleCode(tag.comment),
                default: tag => defaultValue = tag.comment || '',
            });
            if (member.type) {
                type = member.type.getFullText();
            }

            result.push({
                name,
                description,
                type,
                defaultValue,
            });
        }
    }

    return result;
}

function renderInterface(interfaceInfo: InterfaceInfo, knownTypeMap: Map<string, string>): string {
    const { title, weight, category, description, members } = interfaceInfo;
    let output = '';
    output += generateFrontMatter(title, weight);
    output += `\n\n# ${title}\n\n`;
    output += `${description}\n\n`;

    for (const member of members) {
        const type = renderType(member.type, knownTypeMap);
        output += `### ${member.name}\n\n`;
        output += `{{< member-info type="${type}" ${member.defaultValue ? `default="${member.defaultValue}" ` : ''}>}}\n\n`;
        output += `${member.description}\n\n`;
    }

    return output;
}

/**
 * Extracts the "@docsCategory" value from the JSDoc comments if present.
 */
function getDocsCategory(statement: ts.InterfaceDeclaration): string {
    let category = '';
    parseTags(statement, {
        docsCategory: tag => category = tag.comment || '',
    });
    return category;
}

/**
 * Parses the Node's JSDoc tags and invokes the supplied functions against any matching tag names.
 */
function parseTags<T extends ts.Node>(node: T, tagMatcher: { [tagName: string]: (tag: ts.JSDocTag) => void; }): void {
    const jsDocTags = ts.getJSDocTags(node);
    for (const tag of jsDocTags) {
        const tagName = tag.tagName.text;
        if (tagMatcher[tagName]) {
            tagMatcher[tagName](tag);
        }
    }
}

function renderType(type: string, knownTypeMap: Map<string, string>): string {
    let typeText = type.trim().replace(/[\u00A0-\u9999<>\&]/gim, i => {
       return '&#' + i.charCodeAt(0) + ';';
    });
    for (const [key, val] of knownTypeMap) {
        typeText = typeText.replace(key, `<a href='${docsPath}${val}/'>${key}</a>`);
    }
    return typeText;
}

/**
 * Generates the Hugo front matter with the title of the document
 */
function generateFrontMatter(title: string, weight: number): string {
    return `---
title: "${title}"
weight: ${weight}
generated: true
---
<!-- This file was generated from the Vendure TypeScript source. Do not modify. Instead, re-run "generate-docs" -->
`;
}

/**
 * Reads the @docsWeight JSDoc tag from the interface.
 */
function getInterfaceWeight(statement: ts.InterfaceDeclaration): number {
    let weight = 10;
    parseTags(statement, {
        docsWeight: tag => weight = Number.parseInt(tag.comment || '10', 10),
    });
    return weight;
}

/**
 * Reads the @description JSDoc tag from the interface.
 */
function getInterfaceDescription(statement: ts.InterfaceDeclaration): string {
    let description = '';
    parseTags(statement, {
        description: tag => description += tag.comment,
    });
    return description;
}

/**
 * Cleans up a JSDoc "@example" block by removing leading whitespace and asterisk (TypeScript has an open issue
 * wherein the asterisks are not stripped as they should be, see https://github.com/Microsoft/TypeScript/issues/23517)
 */
function formatExampleCode(example: string = ''): string {
    return '\n\n' + example.replace(/\n\s+\*\s/g, '');
}