#!/usr/bin/env bun

// Shared helper for recurring coding agent workflows.
//
// `footer` mode appends visible /iterate instructions plus a hidden workflow marker
// to agent-created PR bodies. The marker is what lets many workflows listen for the
// same /iterate command while only the workflow that opened the PR continues.
//
// `prompt` mode builds the iteration prompt after the workflow has passed its cheap
// pre-check and checked out the PR branch. It intentionally includes raw PR context
// plus the workflow memory file, then asks the agent to update the PR and distill
// durable guidance back into that memory file when appropriate.
//
// Installation options:
// 1. Place in `.github/scripts/agent-iteration.ts` (recommended)
// 2. Place in `ci-scripts/agent-iteration.ts`
// 3. Place in `scripts/agent-iteration.ts`
//
// Usage:
//   bun .github/scripts/agent-iteration.ts --command footer --workflow <workflow-id> --memory <memory-path>
//   bun .github/scripts/agent-iteration.ts --command prompt --workflow <workflow-id> --memory <memory-path> --repo <owner/repo> --pr-number <number> --comment-body <body>

interface Args {
	command: 'footer' | 'prompt'
	workflow: string
	memory: string
	repo?: string
	prNumber?: string
	commentBody?: string
}

const args = parseArgs(Bun.argv.slice(2))

if (args.command === 'footer') {
	process.stdout.write(renderFooter(args.workflow, args.memory))
} else {
	if (!args.repo || !args.prNumber) throw new Error('--repo and --pr-number are required for prompt')
	process.stdout.write(await renderIterationPrompt(args))
}

function renderFooter(workflow: string, memory: string): string {
	return `
---

### Iterating on this agent run

This PR was opened by a coding agent workflow. Maintainers can comment:

- \`/iterate <feedback>\` to ask the same workflow to update this PR and learn durable guidance for future runs.

The workflow stores durable feedback in its agent memory file and injects that memory into future runs.

<!-- codelayer-agent:workflow=${workflow};memory=${memory};version=1 -->
`.trim()
}

async function renderIterationPrompt(args: Args): Promise<string> {
	const memory = await readTextIfExists(args.memory)
	const pr = await ghJson(`repos/${args.repo}/pulls/${args.prNumber}`)
	const [issueComments, reviewComments] = await Promise.all([
		ghJson(`repos/${args.repo}/issues/${args.prNumber}/comments --paginate`),
		ghJson(`repos/${args.repo}/pulls/${args.prNumber}/comments --paginate`),
	])

	return `# Iteration Request

${stripIterateCommand(args.commentBody ?? '')}

# Workflow Identity

- Workflow: ${args.workflow}
- Agent memory file: ${args.memory}

# Instructions

You are iterating on an open PR that was created by this coding agent workflow.

1. Treat the Iteration Request as the user's current instruction.
2. Update this PR branch if the feedback asks for a code, workflow, prompt, or documentation change.
3. Distill durable feedback into ${args.memory} when it should influence future scheduled/manual runs of this workflow.
4. Keep ${args.memory} concise and human-readable. Do not append raw transcripts or one-off PR details.
5. If the feedback is only PR-specific, update the PR but do not add it to memory.
6. Commit and push any changes you make.
7. Finish with a concise GitHub-flavored markdown summary of what changed and whether memory was updated.

# Current Agent Memory

${memory || '(memory file is empty or missing)'}

# Pull Request

- Number: #${pr.number}
- Title: ${pr.title}
- State: ${pr.state}
- Base: ${pr.base?.ref ?? '(unknown)'}
- Head: ${pr.head?.ref ?? '(unknown)'}

## PR Body

${pr.body ?? '(empty)'}

# PR Issue Comments

${formatIssueComments(issueComments)}

# PR Review Comments

${formatReviewComments(reviewComments)}
`
}

async function readTextIfExists(path: string): Promise<string> {
	try {
		const file = Bun.file(path)
		if (!(await file.exists())) return ''
		return await file.text()
	} catch {
		return ''
	}
}

async function ghJson(pathAndArgs: string): Promise<any> {
	const result = await Bun.$`bash -lc ${`gh api ${pathAndArgs}`}`.text()
	return JSON.parse(result)
}

function formatIssueComments(comments: any): string {
	if (!Array.isArray(comments) || comments.length === 0) return '(no issue comments)'
	return comments
		.map((comment) => {
			return `Comment ${comment.id} by ${comment.user?.login ?? 'unknown'} at ${comment.created_at ?? 'unknown time'}:\n\n${comment.body ?? ''}`
		})
		.join('\n\n---\n\n')
}

function formatReviewComments(comments: any): string {
	if (!Array.isArray(comments) || comments.length === 0) return '(no review comments)'
	return comments
		.map((comment) => {
			return `Review comment ${comment.id} by ${comment.user?.login ?? 'unknown'} on ${comment.path ?? 'unknown path'}:${comment.line ?? comment.original_line ?? 'unknown line'} at ${comment.created_at ?? 'unknown time'}:\n\n${comment.body ?? ''}`
		})
		.join('\n\n---\n\n')
}

function stripIterateCommand(body: string): string {
	return body.trim().replace(/^\/iterate\b\s*/i, '').trim() || 'Iterate on this PR using the available feedback.'
}

function parseArgs(argv: string[]): Args {
	const parsed: Record<string, string> = {}
	for (let i = 0; i < argv.length; i += 1) {
		const arg = argv[i]
		if (!arg?.startsWith('--')) continue
		const key = arg.slice(2)
		const value = argv[i + 1]
		if (!value || value.startsWith('--')) throw new Error(`Missing value for ${arg}`)
		parsed[key] = value
		i += 1
	}

	const command = parsed.command
	if (command !== 'footer' && command !== 'prompt') throw new Error('--command must be footer or prompt')
	if (!parsed.workflow) throw new Error('--workflow is required')
	if (!parsed.memory) throw new Error('--memory is required')

	return {
		command,
		workflow: parsed.workflow,
		memory: parsed.memory,
		repo: parsed.repo,
		prNumber: parsed['pr-number'],
		commentBody: parsed['comment-body'],
	}
}