/**
 * Pi adapter for the official codebase-memory-mcp hook frontend.
 *
 * CBM owns project resolution, canonical paths, query formatting, coverage,
 * deadlines, and fail-open behavior. This adapter only translates Pi events
 * into the documented `hook-augment` payload and attaches the returned
 * additionalContext to Pi's event/result surface.
 */

import type {
	ExtensionAPI,
	FindToolInput,
	GrepToolInput,
	ReadToolInput,
} from "@earendil-works/pi-coding-agent";

import { describeError } from "./cbm-lifecycle.ts";
import { runOfficialHook, type HookPayload } from "./cbm-native.ts";

const DISABLED = /^(1|true)$/i.test(process.env.CBM_HOOKS_DISABLE ?? "");
const DEBUG = /^(1|true)$/i.test(process.env.CBM_HOOKS_DEBUG ?? "");

function debug(message: string): void {
	if (DEBUG) process.stderr.write(`[cbm-graph-context] ${message}\n`);
}

function textBlock(text: string): { type: "text"; text: string } {
	return { type: "text", text };
}

function toolPayload(
	toolName: string,
	input: Record<string, unknown>,
	cwd: string,
): HookPayload | null {
	if (toolName === "grep") {
		const grep = input as GrepToolInput;
		if (typeof grep.pattern !== "string" || !grep.pattern) return null;
		return {
			hook_event_name: "PreToolUse",
			cwd,
			tool_name: "Grep",
			tool_input: {
				pattern: grep.pattern,
				...(typeof grep.path === "string" ? { path: grep.path } : {}),
			},
		};
	}
	if (toolName === "find") {
		const find = input as FindToolInput;
		if (typeof find.pattern !== "string" || !find.pattern) return null;
		return {
			hook_event_name: "PreToolUse",
			cwd,
			tool_name: "Glob",
			tool_input: {
				pattern: find.pattern,
				...(typeof find.path === "string" ? { path: find.path } : {}),
			},
		};
	}
	if (toolName === "read") {
		const read = input as ReadToolInput;
		if (typeof read.path !== "string" || !read.path) return null;
		return {
			hook_event_name: "PostToolUse",
			cwd,
			tool_name: "Read",
			tool_input: { file_path: read.path },
		};
	}
	return null;
}

export default function (pi: ExtensionAPI): void {
	if (DISABLED) {
		debug("disabled by CBM_HOOKS_DISABLE");
		return;
	}

	pi.on("before_agent_start", async (event, ctx) => {
		try {
			const payload: HookPayload = {
				hook_event_name: "SessionStart",
				cwd: ctx.cwd,
			};
			const context = await runOfficialHook(payload, ctx.signal);
			if (!context || event.systemPrompt.includes(context.text)) return;
			return { systemPrompt: `${event.systemPrompt}\n\n${context.text}` };
		} catch (error) {
			debug(`before_agent_start failed: ${describeError(error)}`);
		}
	});

	pi.on("tool_result", async (event, ctx) => {
		if (event.isError) return;
		const payload = toolPayload(event.toolName, event.input, ctx.cwd);
		if (!payload) return;
		try {
			const context = await runOfficialHook(payload, ctx.signal);
			if (!context || event.content.some((item) => item.type === "text" && item.text.includes(context.text))) return;
			return { content: [textBlock(context.text), ...event.content] };
		} catch (error) {
			debug(`tool_result failed: ${describeError(error)}`);
		}
	});
}