const makeFilenameRewriter = (filenameRewriters) => (filename, line, column) => (
  Object.entries(filenameRewriters)
    .reduce(
      (filename, [from, to]) => filename.replace(new RegExp(from), to),
      [filename, ...(line ? [line, column] : [])].join(':'),
    )
);

exports.generateBuildFilesPage = (buildFiles) => {
  const source = [];
  source.push('---');
  source.push('title: Build files');
  source.push('description: All the build files in this project.');
  source.push('---');
  source.push('');
  source.push('This page documents all the build configuration files in this project.');
  source.push('');
  if (buildFiles.length > 0) {
    buildFiles
      .sort(({filename: l}, {filename: r}) => (l < r ? -1 : 1))
      .forEach(({filename, description}) => {
        source.push(`## \`${filename}\``);
        source.push('');
        source.push(description);
        source.push('');
      });
  }
  return source.join('\n');
};

exports.generateConfigPage = (configs) => {
  const source = [];
  source.push('---');
  source.push('title: Fleck configuration');
  source.push('description: All the configurable flecks in this project.');
  source.push('---');
  source.push('');
  source.push("import CodeBlock from '@theme/CodeBlock';");
  source.push('');
  source.push('<style>td > .theme-code-block \\{ margin: 0; \\}</style>');
  source.push('');
  source.push('This page documents all configurable flecks in this project.');
  source.push('');
  Object.entries(configs)
    .sort(([l], [r]) => (l < r ? -1 : 1))
    .forEach(([fleck, configs]) => {
      source.push(`## \`${fleck}\``);
      source.push('|Name|Default|Description|');
      source.push('|-|-|-|');
      configs.forEach(({defaultValue, description, key}) => {
        // Leading and trailing empty cell to make table rendering easier.
        const row = ['', key];
        let code = defaultValue.replace(/`/g, '\\`');
        // Multiline code. Fix indentation.
        if (defaultValue.includes('\n')) {
          const defaultValueLines = code.split('\n');
          const [first, ...rest] = defaultValueLines;
          const indent = (rest[0].length - rest[0].trimStart().length) - 2;
          code = [first, ...rest.map((line) => line.substring(indent))].join('\\n');
        }
        row.push(`<CodeBlock language="javascript">{\`${code}\`}</CodeBlock>`);
        row.push(description, '');
        source.push(row.join('|'));
      });
      source.push('');
    });
  return source.join('\n');
};

exports.generateHookPage = (hooks, flecks) => {
  const {filenameRewriters} = flecks.get('@flecks/dox');
  const rewriteFilename = makeFilenameRewriter(filenameRewriters);
  const source = [];
  source.push('---');
  source.push('title: Hooks');
  source.push('description: All the hooks in this project.');
  source.push('---');
  source.push('');
  source.push('This page documents all the hooks in this project.');
  source.push('');
  Object.entries(hooks)
    .sort(([lhook], [rhook]) => (lhook < rhook ? -1 : 1))
    .forEach(([hook, {implementations = [], invocations = [], specification}]) => {
      const {description, example, params} = specification || {
        params: [],
      };
      source.push(`## \`${hook}\``);
      source.push('');
      if (description) {
        source.push(...description.split('\n'));
        source.push('');
      }
      if (example) {
        source.push('### Example usage');
        source.push('');
        source.push('```javascript');
        source.push('export const hooks = {');
        source.push(`  '${hook}': ${example}`);
        source.push('};');
        source.push('```');
        source.push('');
      }
      if (params.length > 0) {
        params.forEach(({description, name, type}) => {
          source.push(`### <code>${name}: ${type}</code>`);
          source.push('');
          source.push(`<p>${description.trim()}</p>`);
          source.push('');
        });
        source.push('');
      }
      if (implementations.length > 0) {
        source.push('<details>');
        source.push('<summary>Implementations</summary>');
        source.push('<ul>');
        implementations.forEach(({filename, column, line}) => {
          source.push(`<li>${rewriteFilename(filename, line, column)}</li>`);
        });
        source.push('</ul>');
        source.push('</details>');
        source.push('');
      }
      if (invocations.length > 0) {
        source.push('<details>');
        source.push('<summary>Invocations</summary>');
        source.push('<ul>');
        invocations.forEach(({filename, column, line}) => {
          source.push(`<li>${rewriteFilename(filename, line, column)}</li>`);
        });
        source.push('</ul>');
        source.push('</details>');
        source.push('');
      }
    });
  return source.join('\n');
};

exports.generateTodoPage = (todos, flecks) => {
  const {filenameRewriters} = flecks.get('@flecks/dox');
  const rewriteFilename = makeFilenameRewriter(filenameRewriters);
  const source = [];
  source.push('---');
  source.push('title: TODO list');
  source.push('description: All the TODO items in this project.');
  source.push('---');
  source.push('');
  source.push("import CodeBlock from '@theme/CodeBlock';");
  source.push('');
  source.push('This page documents all the TODO items in this project.');
  source.push('');
  if (todos.length > 0) {
    todos.forEach(({
      filename,
      context,
      description,
    }) => {
      source.push(rewriteFilename(filename));
      source.push(`> ## ${description}`);
      source.push(`> <CodeBlock>${context}</CodeBlock>`);
      source.push('');
    });
    source.push('');
  }
  return source.join('\n');
};