import { readdirSync, readFileSync, writeFileSync } from 'fs'
import { UserScriptMetaFull } from './types'

export interface readmeData {
    meta: UserScriptMetaFull
    error: string | null
}

export function updateReadmeFile(fileList: readmeData[]) {
    let readmeFile = getReadmeFileName()
    if (readmeFile !== null) {
        let [readmeStart, readmeEnd] = readReadmeFile(readmeFile)

        let installLinks = fileList.map(readmeDataToString).join('\n')

        let installLinksAll = `<!-- START INSTALL LINKS -->
## Installs

${installLinks}
<!-- END INSTALL LINKS -->`

        let content = readmeStart + installLinksAll + readmeEnd
        writeFileSync(readmeFile, content)
    }
}

function readmeDataErrorString(error: string | null): string {
    if (error === null) return ''
    error = error
        .split('\n')
        .map(line => `    ${line}`)
        .join('\n')
    return `\n\n${error}`
}

function readmeDataToString(readmeData: readmeData): string {
    let { meta, error } = readmeData
    let errStr = error !== null ? '~~' : ''
    let errMsg = readmeDataErrorString(error)
    return `- ${errStr}[${meta.name}](${meta.downloadURL})})${errStr}${errMsg}`
}

function getReadmeFileName(): string | null {
    let files = readdirSync('.')
    for (let name of files) {
        if (/^readme\.md$/i.test(name)) {
            return name
        }
    }
    return null
}

function readReadmeFile(readmeFile: string): [string, string] {
    const content = readFileSync(readmeFile).toString()

    const regex =
        /<!-- START INSTALL LINKS -->(?:.|\n)*?<!-- END INSTALL LINKS -->/
    const index = regex.exec(content)?.index

    let contentPre = '',
        contentPost = ''

    if (index === undefined) {
        contentPre = content
    } else {
        let content_replace = content.replace(regex, '')
        contentPre = content_replace.slice(0, index)
        contentPost = content_replace.slice(index)
    }

    if (contentPre.trimEnd().length === 0) contentPre = ''
    else contentPre = contentPre.trimEnd() + '\n\n'

    if (contentPost.trimStart().length === 0) contentPost = '\n'
    else contentPost = '\n\n' + contentPost.trimStart()

    return [contentPre, contentPost]
}