#!/usr/bin/env bun
/**
 * Graphite gatherer for status
 *
 * Collects stack and branch data via `gt` CLI:
 * - Stack structure and hierarchy
 * - Branch PR status
 * - Restack/submit needs
 * - Recent commits via git
 */

import { parseArgs } from "node:util";
import { parseTimeConstraint, toGitSince } from "../lib/time";
import type {
	GathererResult,
	GraphiteBranch,
	GraphiteData,
} from "../lib/types";

const { values } = parseArgs({
	args: Bun.argv.slice(2),
	options: {
		time: { type: "string", short: "t", default: "24h" },
		help: { type: "boolean", short: "h" },
	},
});

if (values.help) {
	console.log(`
graphite-gatherer.ts - Gather Graphite stack data

Usage:
  ./graphite-gatherer.ts [options]

Options:
  -t, --time <constraint>   Time constraint for commits (24h, 7d, 2w) [default: 24h]
  -h, --help               Show this help

Output:
  JSON GathererResult with GraphiteData
`);
	process.exit(0);
}

/**
 * Result of running a shell command.
 */
interface CmdOutput {
	success: boolean;
	stdout: string;
	stderr: string;
}

/**
 * Runs a shell command and captures output.
 * @param cmd - Command to run
 * @param args - Arguments to pass
 * @returns Command output
 */
async function runCmd(cmd: string, args: string[]): Promise<CmdOutput> {
	const proc = Bun.spawn([cmd, ...args], {
		stdout: "pipe",
		stderr: "pipe",
	});

	const stdout = await new Response(proc.stdout).text();
	const stderr = await new Response(proc.stderr).text();
	const exitCode = await proc.exited;

	return { success: exitCode === 0, stdout, stderr };
}

/**
 * Checks if Graphite CLI is installed.
 * @returns True if gt is available
 */
async function checkGtAvailable(): Promise<boolean> {
	const result = await runCmd("which", ["gt"]);
	return result.success;
}

/**
 * Checks if current directory is a git repository.
 * @returns True if in a git repo
 */
async function checkGitRepo(): Promise<boolean> {
	const result = await runCmd("git", ["rev-parse", "--git-dir"]);
	return result.success;
}

/**
 * Gets Graphite stack state from gt CLI.
 * @returns Stack state or null on failure
 */
async function getGtState(): Promise<{
	branches: GraphiteBranch[];
	stacks: string[][];
	currentBranch: string;
	trunk: string;
} | null> {
	// Get structured state from gt
	const result = await runCmd("gt", ["log", "--json"]);

	if (!result.success) {
		// Try alternate: gt state
		const stateResult = await runCmd("gt", ["state"]);
		if (!stateResult.success) return null;

		// Parse text output as fallback
		return parseGtStateText(stateResult.stdout);
	}

	try {
		const data = JSON.parse(result.stdout);
		return parseGtLogJson(data);
	} catch {
		return null;
	}
}

/**
 * Parses JSON output from gt log command.
 * @param data - Raw JSON data
 * @returns Structured Graphite state
 */
function parseGtLogJson(data: unknown): {
	branches: GraphiteBranch[];
	stacks: string[][];
	currentBranch: string;
	trunk: string;
} {
	// gt log --json returns array of branch entries
	const entries = Array.isArray(data) ? data : [];

	const branchMap = new Map<string, GraphiteBranch>();
	let currentBranch = "main";
	const trunk = "main";

	for (const entry of entries) {
		const branch: GraphiteBranch = {
			name: entry.branch || entry.name || "",
			prNumber: entry.pr?.number,
			prStatus: mapPrState(entry.pr?.state, entry.pr?.isDraft),
			prUrl: entry.pr?.url,
			parent: entry.parent,
			children: [],
			isCurrent: entry.isCurrent || entry.current || false,
			needsRestack: entry.needsRestack || false,
			needsSubmit: entry.needsSubmit || false,
			commitCount: entry.commitCount || entry.commits?.length || 0,
		};

		if (branch.isCurrent) {
			currentBranch = branch.name;
		}

		branchMap.set(branch.name, branch);
	}

	// Build children relationships
	for (const branch of branchMap.values()) {
		if (branch.parent && branchMap.has(branch.parent)) {
			branchMap.get(branch.parent)?.children.push(branch.name);
		}
	}

	// Build stacks (branches that share a root)
	const stacks = buildStacks(branchMap, trunk);

	return {
		branches: Array.from(branchMap.values()),
		stacks,
		currentBranch,
		trunk,
	};
}

/**
 * Parses text output from gt state command (fallback).
 * @param text - Raw text output
 * @returns Structured Graphite state
 */
function parseGtStateText(text: string): {
	branches: GraphiteBranch[];
	stacks: string[][];
	currentBranch: string;
	trunk: string;
} {
	// Fallback parser for text output
	const lines = text.split("\n").filter((l) => l.trim());
	const branches: GraphiteBranch[] = [];
	let currentBranch = "main";

	for (const line of lines) {
		// Look for branch indicators like "◉ branch-name" or "○ branch-name"
		const match = line.match(/[◉○●◐]\s+(\S+)/);
		if (match) {
			const name = match[1];
			const isCurrent = line.includes("◉") || line.includes("●");
			if (isCurrent) currentBranch = name;

			branches.push({
				name,
				children: [],
				isCurrent,
				needsRestack: line.includes("restack"),
				needsSubmit: line.includes("submit"),
				commitCount: 0,
			});
		}
	}

	return {
		branches,
		stacks: branches.length > 0 ? [branches.map((b) => b.name)] : [],
		currentBranch,
		trunk: "main",
	};
}

/**
 * Maps PR state from API to internal status.
 * @param state - API state string
 * @param isDraft - Whether PR is a draft
 * @returns Normalized status
 */
function mapPrState(
	state?: string,
	isDraft?: boolean,
): "draft" | "open" | "ready" | "merged" | "closed" | undefined {
	if (!state) return undefined;
	if (isDraft) return "draft";

	switch (state.toLowerCase()) {
		case "open":
			return "open";
		case "merged":
			return "merged";
		case "closed":
			return "closed";
		default:
			return "open";
	}
}

/**
 * Builds stack arrays from branch relationships.
 * @param branchMap - Map of branch names to branch data
 * @param trunk - Trunk branch name
 * @returns Array of stacks (each stack is array of branch names)
 */
function buildStacks(
	branchMap: Map<string, GraphiteBranch>,
	trunk: string,
): string[][] {
	const stacks: string[][] = [];
	const visited = new Set<string>();

	// Find root branches (parent is trunk or undefined)
	const roots = Array.from(branchMap.values()).filter(
		(b) => !b.parent || b.parent === trunk || !branchMap.has(b.parent),
	);

	for (const root of roots) {
		if (visited.has(root.name)) continue;

		const stack: string[] = [];
		const queue = [root.name];

		while (queue.length > 0) {
			const name = queue.shift();
			if (!name || visited.has(name)) continue;

			visited.add(name);
			stack.push(name);

			const branch = branchMap.get(name);
			if (branch) {
				queue.push(...branch.children);
			}
		}

		if (stack.length > 0) {
			stacks.push(stack);
		}
	}

	return stacks;
}

/**
 * Gets count of recent commits within time window.
 * @param timeMs - Time window in milliseconds
 * @returns Number of commits
 */
async function getRecentCommits(timeMs: number): Promise<number> {
	const since = toGitSince(timeMs);
	const result = await runCmd("git", ["log", `--since=${since}`, "--oneline"]);

	if (!result.success) return 0;
	return result.stdout.split("\n").filter((l) => l.trim()).length;
}

/**
 * Gathers Graphite stack and branch data.
 * @returns Gatherer result with Graphite data
 */
async function gatherGraphiteData(): Promise<GathererResult<GraphiteData>> {
	const timestamp = new Date().toISOString();

	// Check prerequisites
	const gtAvailable = await checkGtAvailable();
	if (!gtAvailable) {
		return {
			source: "graphite",
			status: "unavailable",
			reason: "gt CLI not installed",
			timestamp,
		};
	}

	const isGitRepo = await checkGitRepo();
	if (!isGitRepo) {
		return {
			source: "graphite",
			status: "unavailable",
			reason: "Not in a git repository",
			timestamp,
		};
	}

	// Parse time constraint
	const timeValue = values.time ?? "24h";
	let timeMs: number;
	try {
		timeMs = parseTimeConstraint(timeValue);
	} catch (e) {
		return {
			source: "graphite",
			status: "error",
			error: e instanceof Error ? e.message : "Invalid time constraint",
			timestamp,
		};
	}

	// Get graphite state
	const state = await getGtState();
	if (!state) {
		return {
			source: "graphite",
			status: "error",
			error: "Failed to parse gt output",
			timestamp,
		};
	}

	// Get recent commit count (informational)
	const _recentCommits = await getRecentCommits(timeMs);

	return {
		source: "graphite",
		status: "success",
		data: {
			currentBranch: state.currentBranch,
			trunk: state.trunk,
			branches: state.branches,
			stacks: state.stacks,
		},
		timestamp,
	};
}

// Main execution
const result = await gatherGraphiteData();
console.log(JSON.stringify(result, null, 2));