oh-my-pi/packages/coding-agent/src/export/html/index.ts

import * as path from "node:path";
import type { AgentState } from "@oh-my-pi/pi-agent-core";
import { APP_NAME, isEnoent } from "@oh-my-pi/pi-utils";
import { getResolvedThemeColors, getThemeExportColors } from "../../modes/theme/theme";
import { type SessionEntry, type SessionHeader, SessionManager } from "../../session/session-manager";
// Pre-generated template (created by scripts/generate-template.ts at publish time)
import { TEMPLATE } from "./template.generated";

export interface ExportOptions {
	outputPath?: string;
	themeName?: string;
}

/** Parse a color string to RGB values. */
function parseColor(color: string): { r: number; g: number; b: number } | undefined {
	const hexMatch = color.match(/^#([0-9a-fA-F]{2})([0-9a-fA-F]{2})([0-9a-fA-F]{2})$/);
	if (hexMatch) {
		return {
			r: Number.parseInt(hexMatch[1], 16),
			g: Number.parseInt(hexMatch[2], 16),
			b: Number.parseInt(hexMatch[3], 16),
		};
	}
	const rgbMatch = color.match(/^rgb\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\)$/);
	if (rgbMatch) {
		return {
			r: Number.parseInt(rgbMatch[1], 10),
			g: Number.parseInt(rgbMatch[2], 10),
			b: Number.parseInt(rgbMatch[3], 10),
		};
	}
	return undefined;
}

/** Calculate relative luminance of a color (0-1, higher = lighter). */
function getLuminance(r: number, g: number, b: number): number {
	const toLinear = (c: number) => {
		const s = c / 255;
		return s <= 0.03928 ? s / 12.92 : ((s + 0.055) / 1.055) ** 2.4;
	};
	return 0.2126 * toLinear(r) + 0.7152 * toLinear(g) + 0.0722 * toLinear(b);
}

/** Adjust color brightness. */
function adjustBrightness(color: string, factor: number): string {
	const parsed = parseColor(color);
	if (!parsed) return color;
	const adjust = (c: number) => Math.min(255, Math.max(0, Math.round(c * factor)));
	return `rgb(${adjust(parsed.r)}, ${adjust(parsed.g)}, ${adjust(parsed.b)})`;
}

/** Derive export background colors from a base color. */
function deriveExportColors(baseColor: string): { pageBg: string; cardBg: string; infoBg: string } {
	const parsed = parseColor(baseColor);
	if (!parsed) {
		return { pageBg: "rgb(24, 24, 30)", cardBg: "rgb(30, 30, 36)", infoBg: "rgb(60, 55, 40)" };
	}

	const luminance = getLuminance(parsed.r, parsed.g, parsed.b);
	if (luminance > 0.5) {
		return {
			pageBg: adjustBrightness(baseColor, 0.96),
			cardBg: baseColor,
			infoBg: `rgb(${Math.min(255, parsed.r + 10)}, ${Math.min(255, parsed.g + 5)}, ${Math.max(0, parsed.b - 20)})`,
		};
	}
	return {
		pageBg: adjustBrightness(baseColor, 0.7),
		cardBg: adjustBrightness(baseColor, 0.85),
		infoBg: `rgb(${Math.min(255, parsed.r + 20)}, ${Math.min(255, parsed.g + 15)}, ${parsed.b})`,
	};
}

/** Generate CSS custom properties for theme. */
async function generateThemeVars(themeName?: string): Promise<string> {
	const colors = await getResolvedThemeColors(themeName);
	const lines: string[] = [];
	for (const [key, value] of Object.entries(colors)) {
		lines.push(`--${key}: ${value};`);
	}

	const themeExport = await getThemeExportColors(themeName);
	const userMessageBg = colors.userMessageBg || "#343541";
	const derived = deriveExportColors(userMessageBg);

	lines.push(`--body-bg: ${themeExport.pageBg ?? derived.pageBg};`);
	lines.push(`--container-bg: ${themeExport.cardBg ?? derived.cardBg};`);
	lines.push(`--info-bg: ${themeExport.infoBg ?? derived.infoBg};`);

	return lines.join(" ");
}

interface SessionData {
	header: SessionHeader | null;
	entries: SessionEntry[];
	leafId: string | null;
	systemPrompt?: string;
	tools?: { name: string; description: string }[];
}

/** Generate HTML from bundled template with runtime substitutions. */
async function generateHtml(sessionData: SessionData, themeName?: string): Promise<string> {
	const themeVars = await generateThemeVars(themeName);
	const sessionDataBase64 = Buffer.from(JSON.stringify(sessionData)).toBase64();

	// Use function replacements so `$'`, `$&`, `$$`, `$n`, etc. in the
	// substituted CSS/base64 are not interpreted as substitution patterns
	// (see https://mdn.io/String.replace).
	return TEMPLATE.replace("<theme-vars/>", () => `<style>:root { ${themeVars} }</style>`).replace(
		"{{SESSION_DATA}}",
		() => sessionDataBase64,
	);
}

/** Export session to HTML using SessionManager and AgentState. */
export async function exportSessionToHtml(
	sm: SessionManager,
	state?: AgentState,
	options?: ExportOptions | string,
): Promise<string> {
	const opts: ExportOptions = typeof options === "string" ? { outputPath: options } : options || {};

	const sessionFile = sm.getSessionFile();
	if (!sessionFile) throw new Error("Cannot export in-memory session to HTML");

	const sessionData: SessionData = {
		header: sm.getHeader(),
		entries: sm.getEntries(),
		leafId: sm.getLeafId(),
		systemPrompt: state?.systemPrompt.join("\n\n"),
		tools: state?.tools?.map(t => ({ name: t.name, description: t.description })),
	};

	const html = await generateHtml(sessionData, opts.themeName);
	const outputPath = opts.outputPath || `${APP_NAME}-session-${path.basename(sessionFile, ".jsonl")}.html`;

	await Bun.write(outputPath, html);
	return outputPath;
}

/** Export session file to HTML (standalone). */
export async function exportFromFile(inputPath: string, options?: ExportOptions | string): Promise<string> {
	const opts: ExportOptions = typeof options === "string" ? { outputPath: options } : options || {};

	let sm: SessionManager;
	try {
		sm = await SessionManager.open(inputPath);
	} catch (err) {
		if (isEnoent(err)) throw new Error(`File not found: ${inputPath}`);
		throw err;
	}

	const sessionData: SessionData = {
		header: sm.getHeader(),
		entries: sm.getEntries(),
		leafId: sm.getLeafId(),
	};

	const html = await generateHtml(sessionData, opts.themeName);
	const outputPath = opts.outputPath || `${APP_NAME}-session-${path.basename(inputPath, ".jsonl")}.html`;

	await Bun.write(outputPath, html);
	return outputPath;
}