module.exports.compileTemplate = compileTemplate

module.exports.processHandlebarFile = processHandlebarFile

module.exports.writeTemplate = writeTemplate

const Handlebars = require('handlebars')

const debug = require('../debug').errors

const { processFile, readFile, writeFile } = require('./fs-utils')

async function compileTemplate (filePath) {

const indexTemplateSource = readFile(filePath)

return Handlebars.compile(indexTemplateSource)

}

/**

* Reads a file, processes it (performing template substitution), and saves

* back the processed result.

*

* @param filePath {string}

* @param substitutions {Object}

*

* @return {Promise}

*/

async function processHandlebarFile (filePath, substitutions) {

return processFile(filePath, (rawSource) => processHandlebarTemplate(rawSource, substitutions))

}

/**

* Performs a Handlebars string template substitution, and returns the

* resulting string.

*

* @see https://www.npmjs.com/package/handlebars

*

* @param source {string} e.g. 'Hello, {{name}}'

*

* @return {string} Result, e.g. 'Hello, Alice'

*/

function processHandlebarTemplate (source, substitutions) {

try {

const template = Handlebars.compile(source)

return template(substitutions)

} catch (error) {

debug(`Error processing template: ${error}`)

return source

}

}

function writeTemplate (filePath, template, substitutions) {

const source = template(substitutions)

writeFile(filePath, source)

}