import { basename } from "node:path";
import type { ExtensionCommandContext } from "@earendil-works/pi-coding-agent";
import { skillPromptTokens, textTokens } from "../estimate";
import { compactList } from "../format";
import type { Line, Section } from "../types";

/** System prompt breakdown from the structured prompt options. */
export const systemPromptSection = (ctx: ExtensionCommandContext): Section => {
	const opts = ctx.getSystemPromptOptions();
	const fullText = ctx.getSystemPrompt() ?? "";
	const fullTokens = textTokens(fullText);

	const lines: Line[] = [];

	const custom = textTokens(opts?.customPrompt);
	if (custom > 0) lines.push({ label: "custom prompt", tokens: custom });

	const guidelines = textTokens(opts?.promptGuidelines?.join("\n"));
	if (guidelines > 0) lines.push({ label: "guidelines", tokens: guidelines });

	const snippets = textTokens(
		opts?.toolSnippets ? Object.values(opts.toolSnippets).join("\n") : undefined,
	);
	if (snippets > 0) lines.push({ label: "tool snippets", tokens: snippets });

	const appended = textTokens(opts?.appendSystemPrompt);
	if (appended > 0) lines.push({ label: "appended prompt", tokens: appended });

	const files = opts?.contextFiles ?? [];
	const fileLines = files.map((f) => ({ label: basename(f.path), tokens: textTokens(f.content) }));
	if (files.length > 0) {
		lines.push({
			label: `context files (${files.length})`,
			tokens: fileLines.reduce((a, b) => a + b.tokens, 0),
			detail: compactList(fileLines),
		});
	}

	const skills = opts?.skills ?? [];
	const skillLines = skills.map((s) => ({
		label: s.name,
		tokens: skillPromptTokens(s.name, s.description, s.filePath),
	}));
	if (skills.length > 0) {
		lines.push({
			label: `skills (${skills.length})`,
			tokens: skillLines.reduce((a, b) => a + b.tokens, 0),
			detail: compactList(skillLines),
		});
	}

	const partsSum = lines.reduce((a, b) => a + b.tokens, 0);
	const rest = Math.max(0, fullTokens - partsSum);
	if (rest > 0) lines.push({ label: "base prompt / other", tokens: rest });

	return {
		title: "System prompt",
		total: Math.max(fullTokens, partsSum),
		lines,
	};
};