import fs from "node:fs";
import path from "node:path";

import { lookupContextTokens } from "../agents/context.js";
import {
  DEFAULT_CONTEXT_TOKENS,
  DEFAULT_MODEL,
  DEFAULT_PROVIDER,
} from "../agents/defaults.js";
import { resolveConfiguredModelRef } from "../agents/model-selection.js";
import {
  derivePromptTokens,
  normalizeUsage,
  type UsageLike,
} from "../agents/usage.js";
import type { ClawdbotConfig } from "../config/config.js";
import {
  resolveMainSessionKey,
  resolveSessionTranscriptPath,
  type SessionEntry,
  type SessionScope,
} from "../config/sessions.js";
import { VERSION } from "../version.js";
import type {
  ElevatedLevel,
  ReasoningLevel,
  ThinkLevel,
  VerboseLevel,
} from "./thinking.js";

type AgentConfig = NonNullable<ClawdbotConfig["agent"]>;

type QueueStatus = {
  mode?: string;
  depth?: number;
  debounceMs?: number;
  cap?: number;
  dropPolicy?: string;
  showDetails?: boolean;
};

type StatusArgs = {
  agent: AgentConfig;
  sessionEntry?: SessionEntry;
  sessionKey?: string;
  sessionScope?: SessionScope;
  groupActivation?: "mention" | "always";
  resolvedThink?: ThinkLevel;
  resolvedVerbose?: VerboseLevel;
  resolvedReasoning?: ReasoningLevel;
  resolvedElevated?: ElevatedLevel;
  modelAuth?: string;
  queue?: QueueStatus;
  includeTranscriptUsage?: boolean;
  now?: number;
};

const formatAge = (ms?: number | null) => {
  if (!ms || ms < 0) return "unknown";
  const minutes = Math.round(ms / 60_000);
  if (minutes < 1) return "just now";
  if (minutes < 60) return `${minutes}m ago`;
  const hours = Math.round(minutes / 60);
  if (hours < 48) return `${hours}h ago`;
  const days = Math.round(hours / 24);
  return `${days}d ago`;
};

const formatKTokens = (value: number) =>
  `${(value / 1000).toFixed(value >= 10_000 ? 0 : 1)}k`;

export const formatTokenCount = (value: number) => formatKTokens(value);

const formatTokens = (
  total: number | null | undefined,
  contextTokens: number | null,
) => {
  const ctx = contextTokens ?? null;
  if (total == null) {
    const ctxLabel = ctx ? formatKTokens(ctx) : "?";
    return `unknown/${ctxLabel}`;
  }
  const pct = ctx ? Math.min(999, Math.round((total / ctx) * 100)) : null;
  const totalLabel = formatKTokens(total);
  const ctxLabel = ctx ? formatKTokens(ctx) : "?";
  return `${totalLabel}/${ctxLabel}${pct !== null ? ` (${pct}%)` : ""}`;
};

export const formatContextUsageShort = (
  total: number | null | undefined,
  contextTokens: number | null | undefined,
) => `Context ${formatTokens(total, contextTokens ?? null)}`;

const formatCommit = (value?: string | null) => {
  if (!value) return null;
  const trimmed = value.trim();
  if (!trimmed) return null;
  return trimmed.length > 7 ? trimmed.slice(0, 7) : trimmed;
};

const resolveGitHead = (startDir: string) => {
  let current = startDir;
  for (let i = 0; i < 12; i += 1) {
    const gitPath = path.join(current, ".git");
    try {
      const stat = fs.statSync(gitPath);
      if (stat.isDirectory()) {
        return path.join(gitPath, "HEAD");
      }
      if (stat.isFile()) {
        const raw = fs.readFileSync(gitPath, "utf-8");
        const match = raw.match(/gitdir:\s*(.+)/i);
        if (match?.[1]) {
          const resolved = path.resolve(current, match[1].trim());
          return path.join(resolved, "HEAD");
        }
      }
    } catch {
      // ignore missing .git at this level
    }
    const parent = path.dirname(current);
    if (parent === current) break;
    current = parent;
  }
  return null;
};

let cachedCommit: string | null | undefined;
const resolveCommitHash = () => {
  if (cachedCommit !== undefined) return cachedCommit;
  const envCommit =
    process.env.GIT_COMMIT?.trim() || process.env.GIT_SHA?.trim();
  const normalized = formatCommit(envCommit);
  if (normalized) {
    cachedCommit = normalized;
    return cachedCommit;
  }
  try {
    const headPath = resolveGitHead(process.cwd());
    if (!headPath) {
      cachedCommit = null;
      return cachedCommit;
    }
    const head = fs.readFileSync(headPath, "utf-8").trim();
    if (!head) {
      cachedCommit = null;
      return cachedCommit;
    }
    if (head.startsWith("ref:")) {
      const ref = head.replace(/^ref:\s*/i, "").trim();
      const refPath = path.resolve(path.dirname(headPath), ref);
      const refHash = fs.readFileSync(refPath, "utf-8").trim();
      cachedCommit = formatCommit(refHash);
      return cachedCommit;
    }
    cachedCommit = formatCommit(head);
    return cachedCommit;
  } catch {
    cachedCommit = null;
    return cachedCommit;
  }
};

const formatQueueDetails = (queue?: QueueStatus) => {
  if (!queue) return "";
  const depth = typeof queue.depth === "number" ? `depth ${queue.depth}` : null;
  if (!queue.showDetails) {
    return depth ? ` (${depth})` : "";
  }
  const detailParts: string[] = [];
  if (depth) detailParts.push(depth);
  if (typeof queue.debounceMs === "number") {
    const ms = Math.max(0, Math.round(queue.debounceMs));
    const label =
      ms >= 1000
        ? `${ms % 1000 === 0 ? ms / 1000 : (ms / 1000).toFixed(1)}s`
        : `${ms}ms`;
    detailParts.push(`debounce ${label}`);
  }
  if (typeof queue.cap === "number") detailParts.push(`cap ${queue.cap}`);
  if (queue.dropPolicy) detailParts.push(`drop ${queue.dropPolicy}`);
  return detailParts.length ? ` (${detailParts.join(" · ")})` : "";
};

const readUsageFromSessionLog = (
  sessionId?: string,
):
  | {
      input: number;
      output: number;
      promptTokens: number;
      total: number;
      model?: string;
    }
  | undefined => {
  // Transcripts always live at: ~/.clawdbot/sessions/<SessionId>.jsonl
  if (!sessionId) return undefined;
  const logPath = resolveSessionTranscriptPath(sessionId);
  if (!fs.existsSync(logPath)) return undefined;

  try {
    const lines = fs.readFileSync(logPath, "utf-8").split(/\n+/);
    let input = 0;
    let output = 0;
    let promptTokens = 0;
    let model: string | undefined;
    let lastUsage: ReturnType<typeof normalizeUsage> | undefined;

    for (const line of lines) {
      if (!line.trim()) continue;
      try {
        const parsed = JSON.parse(line) as {
          message?: {
            usage?: UsageLike;
            model?: string;
          };
          usage?: UsageLike;
          model?: string;
        };
        const usageRaw = parsed.message?.usage ?? parsed.usage;
        const usage = normalizeUsage(usageRaw);
        if (usage) lastUsage = usage;
        model = parsed.message?.model ?? parsed.model ?? model;
      } catch {
        // ignore bad lines
      }
    }

    if (!lastUsage) return undefined;
    input = lastUsage.input ?? 0;
    output = lastUsage.output ?? 0;
    promptTokens =
      derivePromptTokens(lastUsage) ?? lastUsage.total ?? input + output;
    const total = lastUsage.total ?? promptTokens + output;
    if (promptTokens === 0 && total === 0) return undefined;
    return { input, output, promptTokens, total, model };
  } catch {
    return undefined;
  }
};

export function buildStatusMessage(args: StatusArgs): string {
  const now = args.now ?? Date.now();
  const entry = args.sessionEntry;
  const resolved = resolveConfiguredModelRef({
    cfg: { agent: args.agent ?? {} },
    defaultProvider: DEFAULT_PROVIDER,
    defaultModel: DEFAULT_MODEL,
  });
  const provider =
    entry?.modelProvider ?? resolved.provider ?? DEFAULT_PROVIDER;
  let model = entry?.model ?? resolved.model ?? DEFAULT_MODEL;
  let contextTokens =
    entry?.contextTokens ??
    args.agent?.contextTokens ??
    lookupContextTokens(model) ??
    DEFAULT_CONTEXT_TOKENS;

  let totalTokens =
    entry?.totalTokens ??
    (entry?.inputTokens ?? 0) + (entry?.outputTokens ?? 0);

  // Prefer prompt-size tokens from the session transcript when it looks larger
  // (cached prompt tokens are often missing from agent meta/store).
  if (args.includeTranscriptUsage) {
    const logUsage = readUsageFromSessionLog(entry?.sessionId);
    if (logUsage) {
      const candidate = logUsage.promptTokens || logUsage.total;
      if (!totalTokens || totalTokens === 0 || candidate > totalTokens) {
        totalTokens = candidate;
      }
      if (!model) model = logUsage.model ?? model;
      if (!contextTokens && logUsage.model) {
        contextTokens = lookupContextTokens(logUsage.model) ?? contextTokens;
      }
    }
  }

  const thinkLevel = args.resolvedThink ?? args.agent?.thinkingDefault ?? "off";
  const verboseLevel =
    args.resolvedVerbose ?? args.agent?.verboseDefault ?? "off";
  const reasoningLevel = args.resolvedReasoning ?? "off";
  const elevatedLevel =
    args.resolvedElevated ??
    args.sessionEntry?.elevatedLevel ??
    args.agent?.elevatedDefault ??
    "on";

  const runtime = (() => {
    const sandboxMode = args.agent?.sandbox?.mode ?? "off";
    if (sandboxMode === "off") return { label: "direct" };
    const sessionScope = args.sessionScope ?? "per-sender";
    const mainKey = resolveMainSessionKey({
      session: { scope: sessionScope },
    });
    const sessionKey = args.sessionKey?.trim();
    const sandboxed = sessionKey
      ? sandboxMode === "all" || sessionKey !== mainKey.trim()
      : false;
    const runtime = sandboxed ? "docker" : sessionKey ? "direct" : "unknown";
    return {
      label: `${runtime}/${sandboxMode}`,
    };
  })();

  const updatedAt = entry?.updatedAt;
  const sessionLine = [
    `Session: ${args.sessionKey ?? "unknown"}`,
    typeof updatedAt === "number"
      ? `updated ${formatAge(now - updatedAt)}`
      : "no activity",
  ]
    .filter(Boolean)
    .join(" • ");

  const isGroupSession =
    entry?.chatType === "group" ||
    entry?.chatType === "room" ||
    Boolean(args.sessionKey?.includes(":group:")) ||
    Boolean(args.sessionKey?.includes(":channel:")) ||
    Boolean(args.sessionKey?.startsWith("group:"));
  const groupActivationValue = isGroupSession
    ? (args.groupActivation ?? entry?.groupActivation ?? "mention")
    : undefined;

  const contextLine = [
    `Context: ${formatTokens(totalTokens, contextTokens ?? null)}`,
    `🧹 Compactions: ${entry?.compactionCount ?? 0}`,
  ]
    .filter(Boolean)
    .join(" · ");

  const queueMode = args.queue?.mode ?? "unknown";
  const queueDetails = formatQueueDetails(args.queue);
  const optionParts = [
    `Runtime: ${runtime.label}`,
    `Think: ${thinkLevel}`,
    `Verbose: ${verboseLevel}`,
    reasoningLevel !== "off" ? `Reasoning: ${reasoningLevel}` : null,
    `Elevated: ${elevatedLevel}`,
  ];
  const optionsLine = optionParts.filter(Boolean).join(" · ");
  const activationParts = [
    groupActivationValue ? `👥 Activation: ${groupActivationValue}` : null,
    `🪢 Queue: ${queueMode}${queueDetails}`,
  ];
  const activationLine = activationParts.filter(Boolean).join(" · ");

  const modelLabel = model ? `${provider}/${model}` : "unknown";
  const authLabel = args.modelAuth ? ` · 🔑 ${args.modelAuth}` : "";
  const modelLine = `🧠 Model: ${modelLabel}${authLabel}`;
  const commit = resolveCommitHash();
  const versionLine = `🦞 ClawdBot ${VERSION}${commit ? ` (${commit})` : ""}`;

  return [
    versionLine,
    modelLine,
    `📚 ${contextLine}`,
    `🧵 ${sessionLine}`,
    `⚙️ ${optionsLine}`,
    activationLine,
  ]
    .filter(Boolean)
    .join("\n");
}

export function buildHelpMessage(): string {
  return [
    "ℹ️ Help",
    "Shortcuts: /new reset | /compact [instructions] | /restart relink",
    "Options: /think <level> | /verbose on|off | /reasoning on|off | /elevated on|off | /model <id>",
  ].join("\n");
}