import * as fs from "node:fs";
import * as path from "node:path";
import type { ExtensionConfig, ToolDescriptionMode } from "../shared/types.ts";
import { getAgentDir, getProjectConfigDir } from "../shared/utils.ts";

const CUSTOM_TOOL_DESCRIPTION_FILE = "subagent-tool-description.md";
const CUSTOM_TOOL_DESCRIPTION_MAX_BYTES = 50 * 1024;
const EXTERNAL_CLI_RUNNER_GUIDANCE = "External CLI agents (codex-exec, codex-exec-writer, claude-code, claude-code-writer, cursor-agent, cursor-agent-writer) use their own runner contract and do not support native Pi child options such as model override, structured output, acceptance/agent contract, tool budget, fast mode, fork context, skills, or native Pi tools unless the runner explicitly implements them.";
const WORKFLOW_RESUME_KEY_GUIDANCE = "Each workflow key identifies one result lane: use a new stable workflow key for every distinct retained resume pass; same-key calls are reused only when launch parameters are identical, and incompatible parameters are rejected.";
const WORKFLOW_OUTPUT_BINDING_GUIDANCE = "For durable workflow child files, set output on runs.run/runs.all; task filename prose is not an output declaration, and return the child's outputReference, outputPathMapping, or artifactPaths instead of inventing a literal path.";
const WORKFLOW_LANES_GUIDANCE = "For bounded parallel sequential chains, use runs.lanes([{key,stages:[{key,agent,task},{key,resume:'previous',task},...]}]); first stages run together, later stages sequence per lane, and the bounded board reports lane-local failures. Only an explicit structuredOutput.verdict === 'blocked' blocks a successful stage; reviewer prose is not parsed.";
const WORKFLOW_HOST_GUIDANCE = "For one non-interactive operator-owned command, await runs.host(key,{kind:'command',command,timeoutMs,output?,role?,provider?}). v1 supports only command steps; output is bounded and command failure fails the workflow.";

export const SUBAGENT_SAFETY_GUIDANCE = `SAFETY-CRITICAL SUBAGENT GUIDANCE:
• Use { action: "list" } before execution and only run executable/non-disabled agents.
• Keep execution and management separate: omit action for structured single-child or workflowScript execution; use action only for management/control.
• Async/background runs are the normal default unless config sets asyncByDefault:false; set async:true explicitly when async behavior matters. Use async:false only when the parent must block until completion. Async mode still shows progress. Final reviews and gate checks stay async; needing a result is not a blocking reason. After an async launch, continue independent work only until its next dependency barrier; consume the result before work that depends on it. Do not sleep or poll status just to wait; use subagent_wait only when the current request must finish in this turn.
• ${WORKFLOW_RESUME_KEY_GUIDANCE}
• ${WORKFLOW_OUTPUT_BINDING_GUIDANCE}
• ${WORKFLOW_HOST_GUIDANCE}
• Ordinary child subagents are not orchestrators. Only explicitly configured fanout children may use the child-safe subagent tool, still bounded by depth/session limits.
• Oracle/advisor consultations should use supervisor dialogue for material unknowns when available; request one-shot only when desired.
• Keep one writer for the same cwd/worktree. Use fresh-context read-only reviewers for independent review, then have the parent synthesize and apply fixes.
• Async runs expose asyncId/asyncDir with status.json, events.jsonl, output logs, status via { action: "status", id }, and lifecycle diagnostics via { action: "debug.run", id }. Include output paths and residual risks when reporting results.`;

export const FULL_SUBAGENT_TOOL_DESCRIPTION = `Run one child with { agent, task? }; use { workflowScript } for inline orchestration or { workflowScriptPath } to load it from the request cwd. The script inputs are mutually exclusive. Omit action for execution. Use action only for management/control actions.

EXECUTION:
• ${EXTERNAL_CLI_RUNNER_GUIDANCE}
• Before executing, use { action: "list" } and run only executable/non-disabled configured agents.
• When passing an explicit model to a child (on the call or a runs.run/runs.all item), first call { action: "models" } and copy an exact provider/id; bare ids resolve only when unique in the registry, and agent names (e.g. gpt-pro, advisor) are not model ids. Set per-run thinking with a suffix on the model string (e.g. provider/id:high; off/minimal/low/medium/high/xhigh/max); the suffix wins over the agent's thinking default. The thinking field only applies to action='watchdog.configure' and is ignored on dispatch.
• SINGLE CHILD: { agent:"worker", task:"..." }. This structured form starts exactly one direct child. Fields such as model, context, cwd, worktree, output, budgets, acceptance, and async apply to that child. Do not combine agent/task with action, workflowScript, or workflowScriptPath.
• WORKFLOW SCRIPT: { workflowScript: "return runs.run('main', {agent:'worker', task:'...'})" }. Use stable-key runs.run for one child and await runs.all([{key,agent,task}, ...]) for ordinary parallel children. runs.all resolves to an ordered array, not a key map, so use results[0], array destructuring, or results.map((result) => result.output), not results.<key>. Do not read .output from unawaited runs.run launches. Stored runs.run promises are only for advanced rolling fanout and each must later be observed with direct await, Promise.race, or Promise.all. Ordinary JavaScript provides sequence, branching, filtering, retries, and aggregation. workflowScript is an ordinary JavaScript statement body, so use an explicit return for a useful result. Use top-level await, plain helper functions, or explicit Promise chains; nested async function, arrow, and method helpers are rejected. For task text with Markdown fences or shell blocks, build quoted lines instead of nesting raw template literals: \`const task=["Run:","\`\`\`bash","npm test","\`\`\`"].join("\\n")\`. Scripts normally start async unless config sets asyncByDefault:false; set async:true explicitly when async behavior matters. Pass async:false only when the parent must block until completion, never for final reviews or gates. Same-repo blocking workflows default to a live in-chat card; explicit live-card requires same-repository async:false, so async workflows should omit chatProgress or use auto/off. Workflow-level child controls default onto each runs.run launch, and explicit child fields override them. Use {action:"children.list"} to list recent retained workflow children with resumable/not-resumable reasons. Resume only rows reported resumable. For a simple follow-up or implementation challenge, use {action:"resume", id:"run-id", message:"..."}. Resume keeps the stored agent/model/tool contract. If no resumable child is listed, launch a same-role fallback challenge and label it as fallback. Inside workflowScript, continue one with runs.run(key, {resume:"run-id", task:"follow-up"}); workflow resumes wait for completed output, and loops must continue from each latest returned runId. Await runs.steer(key, message, {mode?, index?, ackTimeoutMs?}) to guide a prior keyed child without exposing its run id; receipts are queued, delivered, missed, or failed. Always await or return runs.steer. For repository mutation lanes, set worktree:true on the workflow or individual runs.run/runs.all item for managed isolation; each parallel child gets a separate worktree and handoff artifact. A workflow usageBudget is enforced once across the workflow. Available globals are runs.run, runs.all, runs.steer, runs.status, runs.ref/refs, emit, console, and standard JavaScript only. Workflows get async state.get(key) and state.set(key, JSONValue) through their automatic or explicit mission; mission:false workflows do not have a state global. Scripts cannot access filesystem, shell, arbitrary Pi tools, or host globals.
• ${WORKFLOW_LANES_GUIDANCE}
• FILE SCRIPT: { workflowScriptPath:"workflows/review.js" }. Relative paths resolve against the request cwd. The host reads the file before the filesystem-free workflow sandbox starts. Do not combine this field with workflowScript.
• Sequential example: { workflowScript: "const a = await runs.run('analyze', {agent:'agent-a', task:'Analyze the request'}); return (await runs.run('plan', {agent:'agent-b', task:'Plan from: '+a.output})).output" }
• Parallel example: { workflowScript: "const [a,b] = await runs.all([{key:'correctness',agent:'agent-a',task:'Review correctness'},{key:'tests',agent:'agent-b',task:'Review tests'}]); return {correctness:a.output,tests:b.output}" }
• Optional context is "fresh", "fork", or "profile". profile requires the selected agent's declared defaultContext and ignores config defaultSubagentContext. Explicit fresh/fork wins. When omitted, config defaultSubagentContext wins over agent defaultContext. Config forkContext can summarize transcript overflow with stable recovery refs before spawn without adding another public context value. timeoutMs/maxRuntimeMs apply to foreground and async workflows; foreground workflows default to 30 minutes and async workflows have no default timeout. Omit acceptance for reviewer/read-only calls; evidence levels end at verified, and acceptance.review.required requests independent writer review.
• Durable mission attachment is automatic by default. Use missionId to attach an existing mission, mission:{...} to override auto-create, or mission:false for ephemeral work. A mission object needs exactly one non-empty title or summary; objective and labels are optional. goal may only be true and requires budget:{tokens}.

MANAGEMENT / CONTROL (use action; omit execution fields):
• validate checks workflowScript or workflowScriptPath syntax and statically decidable structure without launching children. list, get, models, guide, children.list, create, update, delete, eject, disable, enable, reset, status, debug.run, doctor, grant-spawn-budget, worktree.discard, worktree.cleanup (plan-only), lane.status, lane.recordMerge, lane.recordSupersession, refine/refine.show/refine.rollback, mission.create/list/show/update/resolve-decision/attach-run/close, inspector.open/status/close, project.open/status/close, and watchdog actions remain available. Use {action:"guide", topic:"overview"} for packaged current-version help; topics are overview, workflows, agents, missions, observability, tool-reference, configuration, models, watchdog, and extension-api.
• status, interrupt, stop, resume, and steer manage live or persisted runs. Use status view:"fleet" for an overview or view:"transcript" with id and optional index to tail output.
• Create durable project schedules with { action:"schedule.create", id?, name?, at:"+10m" | ISO, workflowScript:"return runs.run('main', {agent:'worker', task:'...'})" }, or use workflowScriptPath instead. Manage them with schedule.list/show/history/pause/resume/run/run-due/delete. This first slice supports fixed intervals; calendar schedules and schedule mission attachment are deferred.

${SUBAGENT_SAFETY_GUIDANCE}`;

export const COMPACT_SUBAGENT_TOOL_DESCRIPTION = `Run one child with { agent, task? }; use { workflowScript } for inline orchestration or { workflowScriptPath } to load it from the request cwd. The script inputs are mutually exclusive. Omit action for execution. Use action only for management/control actions.

EXECUTE:
• ${EXTERNAL_CLI_RUNNER_GUIDANCE}
• Call { action:"list" } first and use only executable/non-disabled agents.
• Passing an explicit model? Call {action:"models"} first and copy an exact provider/id; bare ids resolve only when unique in the registry; agent names (e.g. gpt-pro, advisor) are not model ids. Per-run thinking is a suffix on the model string (provider/id:high; off/minimal/low/medium/high/xhigh/max), and the suffix wins over the agent's thinking default; the thinking field only applies to action='watchdog.configure' and is ignored on dispatch.
• SINGLE {agent:"worker",task:"..."} starts exactly one direct child. Fields apply to that child. Do not combine agent/task with action, workflowScript, or workflowScriptPath.
• SCRIPT {workflowScript:"return runs.run('main', {agent:'worker', task:'...'})"}. Use stable-key runs.run for one child and await runs.all([{key,agent,task}, ...]) for ordinary parallel work. runs.all resolves to an ordered array, not a key map; use results[0], destructuring, or results.map(...), not results.<key>. Do not read .output from unawaited runs.run launches. Stored runs.run promises are only for advanced rolling fanout and each must later be observed with direct await, Promise.race, or Promise.all. Await runs.steer(key,message,options?) to guide a prior keyed child; it returns queued, delivered, missed, or failed and never accepts a raw run id. Always await or return steering calls. Use {action:"children.list"} for recent retained workflow children and resume only rows reported resumable. Use {action:"resume",id:"run-id",message:"..."} for a simple follow-up or challenge; resume keeps the stored agent/model/tool contract. If none is resumable, launch a same-role fallback challenge and label it as fallback. Inside workflowScript use runs.run(key,{resume:"run-id",task:"follow-up"}) when the script must wait for completion and continue from the latest returned runId. Workflows get async state.get/state.set through their automatic or explicit mission; mission:false does not. Scripts are ordinary JavaScript statement bodies; use explicit return for a useful result. Use top-level await, plain helper functions, or explicit Promise chains; nested async function, arrow, and method helpers are rejected. For task text with Markdown fences or shell blocks, build quoted lines instead of nesting raw template literals: \`const task=["Run:","\`\`\`bash","npm test","\`\`\`"].join("\\n")\`. Use JavaScript for sequence, branching, retries, and aggregation. For repository mutation lanes, use worktree:true on the workflow or runs.run/runs.all item for managed isolation. Scripts normally start async unless config sets asyncByDefault:false; set async:true explicitly when async behavior matters. async:false blocks the parent until completion and auto-enables a same-repo live chat card unless chatProgress is off; explicit live-card requires same-repository async:false, so async workflows should omit chatProgress or use auto/off.
• ${WORKFLOW_LANES_GUIDANCE}
• FILE SCRIPT {workflowScriptPath:"workflows/review.js"} loads the script on the host relative to the request cwd before sandbox execution. Do not combine it with workflowScript.
• Example: {workflowScript:"const [a,b]=await runs.all([{key:'a',agent:'agent-a',task:'Implement A',worktree:true},{key:'b',agent:'agent-b',task:'Implement B',worktree:true}]); return [a.output,b.output]"}
• context can be fresh, fork, or profile. profile requires the selected agent's declared defaultContext and ignores defaultSubagentContext. Explicit fresh/fork wins; omitted context follows defaultSubagentContext before agent defaultContext. Config forkContext can summarize transcript overflow with stable recovery refs before spawn without adding another public context value. timeoutMs/maxRuntimeMs apply to foreground and async workflows; foreground workflows default to 30 minutes and async workflows have no default timeout. Omit acceptance for reviewer/read-only calls.

MANAGE / CONTROL:
• Use action without execution fields for list/get/models/guide/authoring, refine/refine.show/refine.rollback, mission, watchdog, status, interrupt, stop, resume, steer, worktree.cleanup (mode:'plan' only), script-only scheduling, diagnostics, and other management actions. guide reads shipped current-version docs by topic.
• A mission object needs exactly one non-empty title or summary; objective and labels are optional. goal may only be true and requires budget:{tokens}.

ASYNC / SAFETY:
• Omitted async follows asyncByDefault config; set async:true explicitly when async behavior matters. Continue independent work only until its next dependency barrier; consume the result before work that depends on it. Do not sleep or poll merely to wait; use subagent_wait only when this turn must receive results.
• ${WORKFLOW_RESUME_KEY_GUIDANCE}
• ${WORKFLOW_OUTPUT_BINDING_GUIDANCE}
• Ordinary children are not orchestrators. Keep one writer per cwd/worktree and use fresh read-only reviewers for independent checks.
• Oracle/advisor consultations use available supervisor dialogue for material unknowns; request one-shot when desired.
• Status and artifacts live under asyncId/asyncDir with status.json, events.jsonl, output logs, and {action:"status",id:"..."}.`;


function isToolDescriptionMode(value: unknown): value is ToolDescriptionMode {
	return value === "full" || value === "compact" || value === "custom";
}

function warn(options: ToolDescriptionOptions | undefined, message: string): void {
	(options?.warn ?? console.warn)(`[pi-subagents] ${message}`);
}

export interface ToolDescriptionOptions {
	cwd?: string;
	agentDir?: string;
	warn?: (message: string) => void;
}

export interface SubagentToolPromptMetadata {
	promptSnippet?: string;
	promptGuidelines?: string[];
}

export function buildSubagentToolPromptMetadata(config: Pick<ExtensionConfig, "toolDescriptionMode"> = {}): SubagentToolPromptMetadata {
	return {};
}

export function resolveToolDescriptionMode(config: Pick<ExtensionConfig, "toolDescriptionMode">, options?: ToolDescriptionOptions): ToolDescriptionMode {
	const mode = config.toolDescriptionMode;
	if (mode === undefined) return "full";
	if (isToolDescriptionMode(mode)) return mode;
	warn(options, `Ignoring invalid toolDescriptionMode ${JSON.stringify(mode)}; expected "full", "compact", or "custom".`);
	return "full";
}

function customDescriptionPaths(options?: ToolDescriptionOptions): string[] {
	const cwd = options?.cwd ?? process.cwd();
	const agentDir = options?.agentDir ?? getAgentDir();
	return [
		path.join(getProjectConfigDir(cwd), CUSTOM_TOOL_DESCRIPTION_FILE),
		path.join(agentDir, CUSTOM_TOOL_DESCRIPTION_FILE),
	];
}

function renderCustomTemplate(template: string, options?: ToolDescriptionOptions): string {
	const cwd = options?.cwd ?? process.cwd();
	const agentDir = options?.agentDir ?? getAgentDir();
	const projectConfigDir = getProjectConfigDir(cwd);
	const variables: Record<string, () => string> = {
		fullDescription: () => FULL_SUBAGENT_TOOL_DESCRIPTION,
		full: () => FULL_SUBAGENT_TOOL_DESCRIPTION,
		compactDescription: () => COMPACT_SUBAGENT_TOOL_DESCRIPTION,
		compact: () => COMPACT_SUBAGENT_TOOL_DESCRIPTION,
		safetyGuidance: () => SUBAGENT_SAFETY_GUIDANCE,
		safety: () => SUBAGENT_SAFETY_GUIDANCE,
		agentDir: () => agentDir,
		projectConfigDir: () => projectConfigDir,
	};
	return template.replace(/\{\{(\w+)\}\}/g, (raw, name: string) => {
		const replacement = variables[name];
		if (replacement) return replacement();
		warn(options, `${CUSTOM_TOOL_DESCRIPTION_FILE}: unknown placeholder ${raw} left unchanged.`);
		return raw;
	});
}

function loadCustomToolDescription(options?: ToolDescriptionOptions): string | undefined {
	for (const filePath of customDescriptionPaths(options)) {
		let stat: fs.Stats;
		try {
			stat = fs.statSync(filePath);
		} catch (error) {
			if (typeof error === "object" && error !== null && "code" in error && (error as NodeJS.ErrnoException).code === "ENOENT") continue;
			warn(options, `Failed to inspect custom tool description '${filePath}': ${error instanceof Error ? error.message : String(error)}`);
			continue;
		}
		if (!stat.isFile()) {
			warn(options, `Ignoring custom tool description '${filePath}' because it is not a file.`);
			continue;
		}
		if (stat.size > CUSTOM_TOOL_DESCRIPTION_MAX_BYTES) {
			warn(options, `Ignoring custom tool description '${filePath}' because it is larger than ${CUSTOM_TOOL_DESCRIPTION_MAX_BYTES} bytes.`);
			continue;
		}
		try {
			const template = fs.readFileSync(filePath, "utf-8").trim();
			if (!template) {
				warn(options, `Ignoring empty custom tool description '${filePath}'.`);
				continue;
			}
			const rendered = renderCustomTemplate(template, options).trim();
			if (!rendered) {
				warn(options, `Ignoring custom tool description '${filePath}' because it rendered empty.`);
				continue;
			}
			return rendered;
		} catch (error) {
			warn(options, `Failed to read custom tool description '${filePath}': ${error instanceof Error ? error.message : String(error)}`);
		}
	}
	return undefined;
}

function withMandatorySafetyGuidance(description: string): string {
	const customDescription = description
		.split(SUBAGENT_SAFETY_GUIDANCE)
		.map((part) => part.trim())
		.filter(Boolean)
		.join("\n\n");
	return customDescription
		? `${customDescription}\n\n${SUBAGENT_SAFETY_GUIDANCE}`
		: SUBAGENT_SAFETY_GUIDANCE;
}

export function buildSubagentToolDescription(config: Pick<ExtensionConfig, "toolDescriptionMode"> = {}, options?: ToolDescriptionOptions): string {
	const mode = resolveToolDescriptionMode(config, options);
	let description: string;
	if (mode === "compact") description = COMPACT_SUBAGENT_TOOL_DESCRIPTION;
	else if (mode === "custom") {
		const custom = loadCustomToolDescription(options);
		if (custom) description = withMandatorySafetyGuidance(custom);
		else {
			warn(options, `${CUSTOM_TOOL_DESCRIPTION_FILE} was not found or valid for toolDescriptionMode "custom"; using full description.`);
			description = FULL_SUBAGENT_TOOL_DESCRIPTION;
		}
	} else description = FULL_SUBAGENT_TOOL_DESCRIPTION;
	return description;
}