gitStatus.ts

import { resolve } from 'node:path'
import { readFile } from 'node:fs/promises'
import { exec } from 'node:child_process'
import { promisify } from 'node:util'

const execp = promisify(exec)

/**
 * @see https://git-scm.com/docs/git-status#_porcelain_format_version_1
 */
const PATTERN = /( M| D|\?\?)\s*(.+)/

function parseGitStatus(line: string) {
    const [, status, path] = line.match(PATTERN) ?? []

    switch (status) {
        case ' M': {
            return [path, 'modified'] as const
        }
        case ' D': {
            return [path, 'deleted'] as const
        }
        case '??': {
            return [path, 'added'] as const
        }
        default: {
            throw new TypeError(`Could not parse git status result: (${line})`)
        }
    }
}

async function loadGitStatus(dirname = process.cwd()) {
    const lines = await execp('git status --porcelain').then(({ stdout }) => stdout.trim().split('\n'))
    const parsedStatus = new Map(lines.map(parseGitStatus))

    return {
        async *[Symbol.asyncIterator]() {
            for (const [relativePath, status] of parsedStatus) {
                const fullpath = resolve(dirname, relativePath)
                const content = await readFile(fullpath, { encoding: 'utf8' })

                yield { fullpath, status, content }
            }
        }
    }
}

const gitStatus = await loadGitStatus()
for await (const changedFile of gitStatus) {
    console.log(changedFile.status, changedFile.fullpath, changedFile.content)
}