import { isAbsolute } from "node:path";
import type { AgentMessage } from "@earendil-works/pi-agent-core";
import type { ToolResultMessage } from "@earendil-works/pi-ai";
import { truncateToWidth, visibleWidth } from "@earendil-works/pi-tui";
import type { EditToolDetails } from "../../../core/tools/edit.js";
import { generateDiffString } from "../../../core/tools/edit-diff.js";
import type { IpythonToolDetails } from "../../../core/tools/ipython.js";
import { resolveToCwd } from "../../../core/tools/path-utils.js";
import { canonicalizePath, formatPathRelativeToCwdOrAbsolute } from "../../../utils/paths.js";
import { theme } from "../theme/theme.js";

export interface FileChangeSummary {
	path: string;
	added: number;
	removed: number;
}

export function countChangedLines(diff: string): { added: number; removed: number } {
	let added = 0;
	let removed = 0;
	for (const line of diff.split("\n")) {
		if (line.startsWith("+")) added++;
		else if (line.startsWith("-")) removed++;
	}
	return { added, removed };
}

function mergeFileChange(target: Map<string, FileChangeSummary>, change: FileChangeSummary, cwd: string): void {
	if (change.added === 0 && change.removed === 0) return;
	const key = canonicalizePath(resolveToCwd(change.path, cwd));
	const existing = target.get(key);
	if (existing) {
		existing.added += change.added;
		existing.removed += change.removed;
	} else {
		target.set(key, { ...change });
	}
}

export function getToolFileChanges(
	toolName: string,
	args: unknown,
	result: { details?: unknown; isError: boolean },
	cwd: string,
): FileChangeSummary[] {
	const changes = new Map<string, FileChangeSummary>();
	if (toolName === "ipython") {
		for (const display of (result.details as IpythonToolDetails | undefined)?.diffs ?? []) {
			const { diff } = generateDiffString(display.oldStr, display.newStr, 4, display.startLine ?? 1);
			mergeFileChange(changes, { path: display.path, ...countChangedLines(diff) }, cwd);
		}
	} else if (toolName === "edit" && !result.isError) {
		const editArgs = args as { path?: unknown; file_path?: unknown } | undefined;
		const path = typeof editArgs?.path === "string" ? editArgs.path : editArgs?.file_path;
		const diff = (result.details as EditToolDetails | undefined)?.diff;
		if (typeof path === "string" && diff) {
			mergeFileChange(changes, { path, ...countChangedLines(diff) }, cwd);
		}
	}
	return [...changes.values()];
}

export function mergeTurnFileChanges(
	target: Map<string, FileChangeSummary>,
	message: AgentMessage,
	toolResults: readonly ToolResultMessage[],
	cwd: string,
): void {
	if (message.role !== "assistant") return;
	const calls = new Map(
		message.content.filter((content) => content.type === "toolCall").map((content) => [content.id, content] as const),
	);
	for (const result of toolResults) {
		const call = calls.get(result.toolCallId);
		if (!call) continue;
		for (const change of getToolFileChanges(call.name, call.arguments, result, cwd)) {
			mergeFileChange(target, change, cwd);
		}
	}
}

/** Dim gutter that anchors every per-file change summary line. */
const FILE_CHANGE_SUMMARY_PREFIX = "    ╰─ ";
/** Standard content inset for full-width diff rows. */
export const FILE_CHANGE_DIFF_INDENT = " ";

function formatChangeCounts(change: Pick<FileChangeSummary, "added" | "removed">): string {
	return `${theme.fg("toolDiffAdded", `+${change.added}`)} ${theme.fg("toolDiffRemoved", `-${change.removed}`)}`;
}

function formatFileChangePath(path: string, cwd: string): string {
	const resolvedPath = resolveToCwd(path, cwd);
	const lexicalPath = formatPathRelativeToCwdOrAbsolute(resolvedPath, cwd);
	if (!isAbsolute(lexicalPath)) return lexicalPath;
	return formatPathRelativeToCwdOrAbsolute(canonicalizePath(resolvedPath), canonicalizePath(cwd));
}

/**
 * One `    ╰─ <path> +N -M` row, truncated to width; the path renders relative
 * to cwd where possible.
 */
export function formatFileChangeSummaryLine(
	rawPath: string,
	cwd: string | undefined,
	change: Pick<FileChangeSummary, "added" | "removed">,
	width: number,
): string {
	const prefix = theme.fg("dim", FILE_CHANGE_SUMMARY_PREFIX);
	const counts = `${theme.fg("dim", " ")}${formatChangeCounts(change)}`;
	const safeWidth = Math.max(1, width);
	const available = Math.max(1, safeWidth - visibleWidth(prefix) - visibleWidth(counts));
	const displayPath = cwd === undefined ? rawPath : formatFileChangePath(rawPath, cwd);
	const path = truncateToWidth(displayPath, available, "…");
	return truncateToWidth(`${prefix}${theme.fg("muted", path)}${counts}`, safeWidth, "");
}

export function formatTotalChangeSummary(changes: readonly FileChangeSummary[]): string {
	const totals = changes.reduce(
		(sum, change) => ({ added: sum.added + change.added, removed: sum.removed + change.removed }),
		{ added: 0, removed: 0 },
	);
	const files = `${changes.length} file${changes.length === 1 ? "" : "s"} changed`;
	return `${theme.fg("muted", files)}${theme.fg("dim", " | ")}${formatChangeCounts(totals)}`;
}