/**
 * commands.ts — pygienium slash-command handlers.
 *
 * Keeps `index.ts` thin: `index.ts` only binds these handlers to pi command
 * names. Each handler accepts the narrow context slice it needs (`cwd`, `mode`,
 * `hasUI`, `ui`) so they are unit-testable without a full pi runtime — tests
 * construct a minimal `PygieniumCtx`.
 *
 * @module pygienium/commands
 */

import type {
	ExtensionCommandContext,
	ExtensionUIContext,
} from "@earendil-works/pi-coding-agent";
import { resolve } from "node:path";
import {
	getAllChecks,
	getCheck,
	type CheckDefinition,
} from "./checks/registry.js";
import { runCheck, parseCheckArgs } from "./modes/check-runner.js";
import { parseAllArgs, runAllChecks, allSummaryPath } from "./modes/all.js";
import { buildPygieniumHelpLines } from "./help.js";
import {
	loadRunState,
	runStatePath,
	saveRunState,
	markRunStatus,
	reconcileRunStatus,
	resetCheckEntry,
	shouldRunOnResume,
} from "./run-state.js";
import { formatRunStatus } from "./status.js";
import {
	exportRun,
	parseExportFilters,
	exportBundlePath,
	type ExportFilters,
} from "./export.js";

/** Narrow context slice handlers need (a subset of `ExtensionCommandContext`). */
export type PygieniumCtx = Pick<
	ExtensionCommandContext,
	"cwd" | "mode" | "hasUI" | "ui"
>;

function print(ctx: PygieniumCtx, line: string): void {
	// In TUI mode, also surface the first line as a notification.
	if (ctx.mode === "tui" && ctx.ui?.notify) {
		ctx.ui.notify(line, "info");
	}
	process.stdout.write(`${line}\n`);
}

/** Resolve an optional `[path]` argument to an absolute cwd. */
function resolveCwd(args: string, ctxCwd: string): string {
	const tok = args.trim().split(/\s+/)[0];
	if (!tok || tok.startsWith("--")) return ctxCwd;
	return resolve(ctxCwd, tok);
}

/** Strip a leading flag token (`--fix`) from args, returning the remainder. */
function splitFlags(args: string): { fix: boolean; rest: string } {
	const tokens = args.trim().length > 0 ? args.trim().split(/\s+/) : [];
	const fix = tokens.includes("--fix");
	const rest = tokens.filter((t) => t !== "--fix").join(" ");
	return { fix, rest };
}

/**
 * Parse `/pygienium-resume` args: an optional `[path]` positional plus the
 * `--fresh` flag.` returns the resolved cwd and whether a fresh re-dispatch
 * is requested.
 */
function parseResumeArgs(
	args: string,
	ctxCwd: string,
): { cwd: string; fresh: boolean } {
	const tokens = args.trim().length > 0 ? args.trim().split(/\s+/) : [];
	const fresh = tokens.includes("--fresh");
	const positional = tokens.find((t) => !t.startsWith("--"));
	const cwd = positional ? resolve(ctxCwd, positional) : ctxCwd;
	return { cwd, fresh };
}

/** `/pygienium-help` */
export async function handleHelpCommand(
	_args: string,
	_ctx: PygieniumCtx,
): Promise<void> {
	for (const line of buildPygieniumHelpLines()) {
		process.stdout.write(`${line}\n`);
	}
}

/**
 * `/pygienium-<check> [path] [--fix]` — the per-check command handler.
 * Exported so `index.ts` can bind one per registered `CheckDefinition` and so
 * tests can invoke it directly with a stub context.
 */
export async function handleCheckCommand(
	check: CheckDefinition,
	args: string,
	ctx: PygieniumCtx,
): Promise<void> {
	const { fix, rest } = splitFlags(args);
	const target = resolveCwd(rest, ctx.cwd);
	const scope = parseCheckArgs(fix ? `--fix ${rest}` : rest, ctx.cwd);

	const outcome = await runCheck({
		check,
		cwd: ctx.cwd,
		scope: { ...scope, cwd: ctx.cwd, target },
		ui: ctx.ui,
		hasUI: ctx.hasUI,
	});

	print(
		ctx,
		`pygienium ${check.label}: ${outcome.status}${outcome.error ? ` — ${outcome.error}` : ""}`,
	);
}

/**
 * `/pygienium-all [path] [--fix] [--fresh] [--only=a,b]` — run every
 * registered check in sequence under a unified status strip, writing
 * `pygienium/all-summary.md`. Delegates to {@link runAllChecks}.
 */
export async function handleAllCommand(
	args: string,
	ctx: PygieniumCtx,
): Promise<void> {
	const checks = getAllChecks();
	if (checks.length === 0) {
		print(ctx, "pygienium: no checks registered.");
		return;
	}
	const parsed = parseAllArgs(args, ctx.cwd);
	const outcome = await runAllChecks({
		cwd: ctx.cwd,
		target: parsed.target,
		fix: parsed.fix,
		fresh: parsed.fresh,
		only: parsed.only,
		ui: ctx.ui,
		hasUI: ctx.hasUI,
	});
	print(
		ctx,
		`pygienium: all-run ${outcome.status} — ${outcome.ran.length} ran, ${outcome.skipped.length} skipped; summary → ${allSummaryPath(ctx.cwd)} (${runStatePath(ctx.cwd)})`,
	);
}

/** `/pygienium-status [path]` — print run-state progress as a line list. */
export async function handleStatusCommand(
	args: string,
	ctx: PygieniumCtx,
): Promise<void> {
	const cwd = resolveCwd(args, ctx.cwd);
	const state = await loadRunState(cwd);
	if (!state) {
		print(ctx, "pygienium: no run state found.");
		return;
	}
	for (const line of formatRunStatus(state)) {
		print(ctx, line);
	}
}

/**
 * `/pygienium-resume [path] [--fresh]` — resume the most recent non-complete
 * run by re-dispatching every check that isn't terminal (`complete`/`skipped`).
 * Pass `--fresh` to re-dispatch even completed checks (their run-state entries
 * are reset and the check re-runs analysis → fix → verify → cleanup fresh).
 */
export async function handleResumeCommand(
	args: string,
	ctx: PygieniumCtx,
): Promise<void> {
	const { cwd, fresh } = parseResumeArgs(args, ctx.cwd);
	let state = await loadRunState(cwd);
	if (!state) {
		print(ctx, "pygienium: no run state to resume.");
		return;
	}

	// Pick the latest resumable run — with the single-file run-state model this
	// is the loaded run unless it's already fully complete AND --fresh wasn't set.
	const resumable = Object.values(state.checks).some((c) =>
		shouldRunOnResume(c, fresh),
	);
	if (!resumable) {
		print(
			ctx,
			`pygienium: run already ${state.status}; nothing to resume (use --fresh to re-run).`,
		);
		return;
	}

	// Re-dispatch this run's checks in stored order, skipping terminal ones
	// unless --fresh.
	let ran = 0;
	let skipped = 0;
	for (const entry of Object.values(state.checks)) {
		const def = getCheck(entry.name);
		if (!def) {
			print(
				ctx,
				`pygienium: check "${entry.name}" is no longer registered; skipping.`,
			);
			skipped++;
			continue;
		}
		if (!shouldRunOnResume(entry, fresh)) {
			skipped++;
			continue;
		}
		if (fresh) {
			resetCheckEntry(state, entry.name);
		}
		print(ctx, `pygienium: resuming ${def.label}…`);
		const outcome = await runCheck({
			check: def,
			cwd,
			scope: { cwd, target: cwd, fix: entry.fix, rest: [] },
			ui: ctx.ui,
			hasUI: ctx.hasUI,
			existingState: state,
		});
		state = outcome.state;
		ran++;
		print(ctx, `pygienium ${def.label}: ${outcome.status}`);
	}

	markRunStatus(state, reconcileRunStatus(state));
	await saveRunState(state);
	print(
		ctx,
		`pygienium: resume done — re-dispatched ${ran}, skipped ${skipped}; run ${state.status} (${runStatePath(cwd)})`,
	);
}

/**
 * `/pygienium-export [path] [--check=<n>[,<n>]] [--status=<s>[,<s>]] [--out=md|json]`
 * — collect every check's `findings.md`/`changes.md` artifacts from
 * `pygienium/checks/<name>/` (and the legacy `.pygienium/checks/` root), apply
 * filters, and write a single bundle to `pygienium/export.{md|json}`.
 */
export async function handleExportCommand(
	args: string,
	ctx: PygieniumCtx,
): Promise<void> {
	const cwd = resolveCwd(args, ctx.cwd);
	const filters: ExportFilters = parseExportFilters(args);
	const state = await loadRunState(cwd);
	const result = await exportRun(cwd, state, filters);
	if (result.entries.length === 0) {
		print(
			ctx,
			`pygienium: nothing to export (no findings.md/changes.md under ${cwd}/pygienium/checks/).`,
		);
		return;
	}
	const filterDesc = [
		filters.check ? `check=${filters.check.join(",")}` : null,
		filters.status ? `status=${filters.status.join(",")}` : null,
	]
		.filter(Boolean)
		.join(" ");
	const suffix = filterDesc ? ` [${filterDesc}]` : "";
	print(
		ctx,
		`pygienium export: ${result.entries.length} check(s) → ${exportBundlePath(cwd, result.format)}${suffix}`,
	);
}

/** A minimal command-registration callback shape (matches `pi.registerCommand`). */
export type RegisterCommandFn = (
	name: string,
	options: {
		description?: string;
		handler: (args: string, ctx: PygieniumCtx) => Promise<void>;
	},
) => void;

/**
 * Auto-register `/pygienium-help` plus one `/pygienium-<check>` per registered
 * `CheckDefinition`, plus the `all`/`resume`/`status`/`export` commands.
 * Called from `index.ts` so that adding a check never requires editing command
 * wiring.
 */
export function registerPygieniumCommands(register: RegisterCommandFn): void {
	register("pygienium-help", {
		description: "Show pygienium commands, checks, and usage.",
		handler: handleHelpCommand,
	});

	for (const def of getAllChecks()) {
		register(`pygienium-${def.name}`, {
			description: def.description,
			handler: (args, ctx) => handleCheckCommand(def, args, ctx),
		});
	}

	register("pygienium-all", {
		description: "Run every registered pygienium check in sequence.",
		handler: handleAllCommand,
	});
	register("pygienium-resume", {
		description: "Resume the most recent in-progress or failed pygienium run.",
		handler: handleResumeCommand,
	});
	register("pygienium-status", {
		description: "Show progress of the current or latest pygienium run.",
		handler: handleStatusCommand,
	});
	register("pygienium-export", {
		description: "Export finalized findings and changes for a pygienium run.",
		handler: handleExportCommand,
	});
}

/** Re-export for index.ts convenience. */
export type { ExtensionUIContext };