const fs = require('fs')
var path = require('path')

/* arguments:
all
frontmatter
*/

// settings
const ignoreFiles = ['_navbar.md', '_sidbar.md']

function loopMdFiles() {
    return fs.readdirSync(__dirname).filter(file => (file.slice(-3) === '.md') && (ignoreFiles.indexOf(file) != 0))
}

// Build vars
var files = []
var args = process.argv.slice(2);
var firstArg = args[0]

if (!firstArg || ['all', 'frontmatter'].indexOf(firstArg) >= 0) {

    // log
    console.log('Update frontmatter ...')

    // loop all markdown files
    loopMdFiles().forEach((file) => {

        // Read file and split into lines
        let lines = fs.readFileSync(file, 'utf8').split(/\r?\n/);

        // Find title
        let title = null
        for (let line of lines) {
            if (line.startsWith('# ') || line.startsWith('## ') || line.startsWith('### ')) {
                // Get title
                title = line.replace('### ','').replace('## ','').replace('# ','')
                break
            }
        }

        // Find title
        let content = []
        let frontmatter = []
        let isFrontmatter = false
        for (let line of lines) {
            if (line.startsWith('---')) {
                isFrontmatter = !isFrontmatter
            }
            if (isFrontmatter && !line.startsWith('---')) {
                frontmatter.push(line)
            }
            if (!isFrontmatter && !line.startsWith('---')) {
                content.push(line)
            }
        }

        // Update frontmatter title
        frontmatterTitle = 'title: ' + title
        let hasFrontmatterTitle = false
        for (let i in frontmatter) {
            line = frontmatter[i]
            if (line.startsWith('title: ')) {
                hasFrontmatterTitle = true
                frontmatter[i] = frontmatterTitle 
            }
        }
        if (!hasFrontmatterTitle) {
            frontmatter.unshift(frontmatterTitle)
        }

        // add footer
        new_content = ['---'].concat(frontmatter, ['---'], content).join('\n')

        // Write content to file
        fs.writeFileSync(file, new_content, 'utf8')
    })

    // log
    console.log('Updating frontmatter.')
}