import fs from "node:fs";
import { redactToolDetail } from "../logging/redact.js";
import { shortenHomeInString } from "../utils.js";

type ToolDisplayActionSpec = {
  label?: string;
  detailKeys?: string[];
};

type ToolDisplaySpec = {
  emoji?: string;
  title?: string;
  label?: string;
  detailKeys?: string[];
  actions?: Record<string, ToolDisplayActionSpec>;
};

type ToolDisplayConfig = {
  version?: number;
  fallback?: ToolDisplaySpec;
  tools?: Record<string, ToolDisplaySpec>;
};

export type ToolDisplay = {
  name: string;
  emoji: string;
  title: string;
  label: string;
  verb?: string;
  detail?: string;
};

const TOOL_DISPLAY_CONFIG: ToolDisplayConfig = (() => {
  try {
    const raw = fs.readFileSync(
      new URL("./tool-display.json", import.meta.url),
      "utf8",
    );
    return JSON.parse(raw) as ToolDisplayConfig;
  } catch {
    return {};
  }
})();
const FALLBACK = TOOL_DISPLAY_CONFIG.fallback ?? { emoji: "🧩" };
const TOOL_MAP = TOOL_DISPLAY_CONFIG.tools ?? {};

function normalizeToolName(name?: string): string {
  return (name ?? "tool").trim();
}

function defaultTitle(name: string): string {
  const cleaned = name.replace(/_/g, " ").trim();
  if (!cleaned) return "Tool";
  return cleaned
    .split(/\s+/)
    .map((part) =>
      part.length <= 2 && part.toUpperCase() === part
        ? part
        : `${part.at(0)?.toUpperCase() ?? ""}${part.slice(1)}`,
    )
    .join(" ");
}

function normalizeVerb(value?: string): string | undefined {
  const trimmed = value?.trim();
  if (!trimmed) return undefined;
  return trimmed.replace(/_/g, " ");
}

function coerceDisplayValue(value: unknown): string | undefined {
  if (value === null || value === undefined) return undefined;
  if (typeof value === "string") {
    const trimmed = value.trim();
    if (!trimmed) return undefined;
    const firstLine = trimmed.split(/\r?\n/)[0]?.trim() ?? "";
    if (!firstLine) return undefined;
    return firstLine.length > 160 ? `${firstLine.slice(0, 157)}…` : firstLine;
  }
  if (typeof value === "number" || typeof value === "boolean") {
    return String(value);
  }
  if (Array.isArray(value)) {
    const values = value
      .map((item) => coerceDisplayValue(item))
      .filter((item): item is string => Boolean(item));
    if (values.length === 0) return undefined;
    const preview = values.slice(0, 3).join(", ");
    return values.length > 3 ? `${preview}…` : preview;
  }
  return undefined;
}

function lookupValueByPath(args: unknown, path: string): unknown {
  if (!args || typeof args !== "object") return undefined;
  let current: unknown = args;
  for (const segment of path.split(".")) {
    if (!segment) return undefined;
    if (!current || typeof current !== "object") return undefined;
    const record = current as Record<string, unknown>;
    current = record[segment];
  }
  return current;
}

function resolveDetailFromKeys(
  args: unknown,
  keys: string[],
): string | undefined {
  for (const key of keys) {
    const value = lookupValueByPath(args, key);
    const display = coerceDisplayValue(value);
    if (display) return display;
  }
  return undefined;
}

function resolveReadDetail(args: unknown): string | undefined {
  if (!args || typeof args !== "object") return undefined;
  const record = args as Record<string, unknown>;
  const path = typeof record.path === "string" ? record.path : undefined;
  if (!path) return undefined;
  const offset = typeof record.offset === "number" ? record.offset : undefined;
  const limit = typeof record.limit === "number" ? record.limit : undefined;
  if (offset !== undefined && limit !== undefined) {
    return `${path}:${offset}-${offset + limit}`;
  }
  return path;
}

function resolveWriteDetail(args: unknown): string | undefined {
  if (!args || typeof args !== "object") return undefined;
  const record = args as Record<string, unknown>;
  const path = typeof record.path === "string" ? record.path : undefined;
  return path;
}

function resolveActionSpec(
  spec: ToolDisplaySpec | undefined,
  action: string | undefined,
): ToolDisplayActionSpec | undefined {
  if (!spec || !action) return undefined;
  return spec.actions?.[action] ?? undefined;
}

export function resolveToolDisplay(params: {
  name?: string;
  args?: unknown;
  meta?: string;
}): ToolDisplay {
  const name = normalizeToolName(params.name);
  const key = name.toLowerCase();
  const spec = TOOL_MAP[key];
  const emoji = spec?.emoji ?? FALLBACK.emoji ?? "🧩";
  const title = spec?.title ?? defaultTitle(name);
  const label = spec?.label ?? name;
  const actionRaw =
    params.args && typeof params.args === "object"
      ? ((params.args as Record<string, unknown>).action as string | undefined)
      : undefined;
  const action = typeof actionRaw === "string" ? actionRaw.trim() : undefined;
  const actionSpec = resolveActionSpec(spec, action);
  const verb = normalizeVerb(actionSpec?.label ?? action);

  let detail: string | undefined;
  if (key === "read") detail = resolveReadDetail(params.args);
  if (!detail && (key === "write" || key === "edit" || key === "attach")) {
    detail = resolveWriteDetail(params.args);
  }

  const detailKeys =
    actionSpec?.detailKeys ?? spec?.detailKeys ?? FALLBACK.detailKeys ?? [];
  if (!detail && detailKeys.length > 0) {
    detail = resolveDetailFromKeys(params.args, detailKeys);
  }

  if (!detail && params.meta) {
    detail = params.meta;
  }

  if (detail) {
    detail = shortenHomeInString(detail);
  }

  return {
    name,
    emoji,
    title,
    label,
    verb,
    detail,
  };
}

export function formatToolDetail(display: ToolDisplay): string | undefined {
  const parts: string[] = [];
  if (display.verb) parts.push(display.verb);
  if (display.detail) parts.push(redactToolDetail(display.detail));
  if (parts.length === 0) return undefined;
  return parts.join(" · ");
}

export function formatToolSummary(display: ToolDisplay): string {
  const detail = formatToolDetail(display);
  return detail
    ? `${display.emoji} ${display.label}: ${detail}`
    : `${display.emoji} ${display.label}`;
}