/**
 * Copy Last Response
 *
 * Shortcuts:
 *   Alt+C  — Copy the last assistant response to clipboard
 *
 * Commands:
 *   /copy-response  — Copy last response to clipboard
 *
 * Text is reflowed: hard line breaks within paragraphs are joined,
 * while paragraph breaks, code blocks, lists, and headers are preserved.
 */

import type { ExtensionAPI, ExtensionContext } from "@mariozechner/pi-coding-agent";
import { spawnSync } from "node:child_process";

type ContentBlock = {
	type?: string;
	text?: string;
};

type SessionEntry = {
	type: string;
	message?: {
		role?: string;
		content?: unknown;
	};
};

function getLastAssistantText(ctx: ExtensionContext): string | null {
	const entries = ctx.sessionManager.getBranch() as SessionEntry[];
	for (let i = entries.length - 1; i >= 0; i--) {
		const entry = entries[i];
		if (entry.type !== "message" || entry.message?.role !== "assistant") continue;

		const content = entry.message.content;
		if (typeof content === "string") return content;
		if (!Array.isArray(content)) continue;

		const texts: string[] = [];
		for (const block of content) {
			if (block && typeof block === "object" && (block as ContentBlock).type === "text" && typeof (block as ContentBlock).text === "string") {
				texts.push((block as ContentBlock).text!);
			}
		}
		if (texts.length > 0) return texts.join("\n");
	}
	return null;
}

/**
 * Reflow text: join hard-wrapped lines within paragraphs, but preserve
 * paragraph breaks, code blocks, list items, headers, and other structure.
 */
function reflowText(raw: string): string {
	const lines = raw.split("\n");
	const result: string[] = [];
	let inCodeBlock = false;
	let paragraph: string[] = [];

	function flushParagraph() {
		if (paragraph.length > 0) {
			result.push(paragraph.join(" "));
			paragraph = [];
		}
	}

	for (const line of lines) {
		if (line.trimStart().startsWith("```")) {
			flushParagraph();
			inCodeBlock = !inCodeBlock;
			result.push(line);
			continue;
		}

		if (inCodeBlock) {
			result.push(line);
			continue;
		}

		const trimmed = line.trimStart();

		if (trimmed === "") {
			flushParagraph();
			result.push("");
			continue;
		}

		if (
			/^#{1,6}\s/.test(trimmed) ||
			/^[-*+]\s/.test(trimmed) ||
			/^\d+[.)]\s/.test(trimmed) ||
			trimmed.startsWith(">") ||
			/^[-*_]{3,}\s*$/.test(trimmed) ||
			trimmed.startsWith("|")
		) {
			flushParagraph();
			result.push(line);
			continue;
		}

		paragraph.push(trimmed);
	}

	flushParagraph();
	return result.join("\n");
}

function copyToClipboard(text: string): boolean {
	const cmds = [
		["wl-copy", []],
		["xclip", ["-selection", "clipboard"]],
		["xsel", ["--clipboard", "--input"]],
	] as const;

	for (const [cmd, args] of cmds) {
		try {
			spawnSync(cmd, [...args], { input: text, stdio: ["pipe", "ignore", "ignore"] });
			return true;
		} catch {
			continue;
		}
	}
	return false;
}


export default function (pi: ExtensionAPI) {
	// --- Shortcut: Alt+C → copy ---
	pi.registerShortcut("alt+c", {
		description: "Copy last assistant response to clipboard",
		handler: async (ctx) => {
			const text = getLastAssistantText(ctx);
			if (!text) { ctx.ui.notify("No assistant response to copy", "warning"); return; }
			const reflowed = reflowText(text);
			if (copyToClipboard(reflowed)) {
				ctx.ui.notify("Response copied to clipboard", "info");
			} else {
				ctx.ui.notify("Failed to copy — no clipboard tool found", "error");
			}
		},
	});


	// --- Command: /copy-response ---
	pi.registerCommand("copy-response", {
		description: "Copy last assistant response to clipboard",
		handler: async (_args, ctx) => {
			const text = getLastAssistantText(ctx);
			if (!text) { ctx.ui.notify("No assistant response to copy", "warning"); return; }
			const reflowed = reflowText(text);
			if (copyToClipboard(reflowed)) {
				ctx.ui.notify("Response copied to clipboard", "info");
			} else {
				ctx.ui.notify("Failed to copy — no clipboard tool found", "error");
			}
		},
	});

}