import fs from "node:fs";

import { lookupContextTokens } from "../agents/context.js";
import {
  DEFAULT_CONTEXT_TOKENS,
  DEFAULT_MODEL,
  DEFAULT_PROVIDER,
} from "../agents/defaults.js";
import { resolveModelAuthMode } from "../agents/model-auth.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 {
  resolveSessionFilePath,
  type SessionEntry,
  type SessionScope,
} from "../config/sessions.js";
import { resolveCommitHash } from "../infra/git-commit.js";
import {
  estimateUsageCost,
  formatTokenCount as formatTokenCountShared,
  formatUsd,
  resolveModelCostConfig,
} from "../utils/usage-format.js";
import { VERSION } from "../version.js";
import { listChatCommands } from "./commands-registry.js";
import type {
  ElevatedLevel,
  ReasoningLevel,
  ThinkLevel,
  VerboseLevel,
} from "./thinking.js";

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

export const formatTokenCount = formatTokenCountShared;

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

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

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

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

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,
  sessionEntry?: SessionEntry,
):
  | {
      input: number;
      output: number;
      promptTokens: number;
      total: number;
      model?: string;
    }
  | undefined => {
  // Transcripts are stored at the session file path (fallback: ~/.clawdbot/sessions/<SessionId>.jsonl)
  if (!sessionId) return undefined;
  const logPath = resolveSessionFilePath(sessionId, sessionEntry);
  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;
  }
};

const formatUsagePair = (input?: number | null, output?: number | null) => {
  if (input == null && output == null) return null;
  const inputLabel = typeof input === "number" ? formatTokenCount(input) : "?";
  const outputLabel =
    typeof output === "number" ? formatTokenCount(output) : "?";
  return `usage ${inputLabel} in / ${outputLabel} out`;
};

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

  let inputTokens = entry?.inputTokens;
  let outputTokens = entry?.outputTokens;
  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, entry);
    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;
      }
      if (!inputTokens || inputTokens === 0) inputTokens = logUsage.input;
      if (!outputTokens || outputTokens === 0) outputTokens = logUsage.output;
    }
  }

  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 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 authMode =
    args.modelAuth ?? resolveModelAuthMode(provider, args.config);
  const showCost = authMode === "api-key";
  const costConfig = showCost
    ? resolveModelCostConfig({
        provider,
        model,
        config: args.config,
      })
    : undefined;
  const hasUsage =
    typeof inputTokens === "number" || typeof outputTokens === "number";
  const cost =
    showCost && hasUsage
      ? estimateUsageCost({
          usage: {
            input: inputTokens ?? undefined,
            output: outputTokens ?? undefined,
          },
          cost: costConfig,
        })
      : undefined;
  const costLabel = showCost && hasUsage ? formatUsd(cost) : undefined;

  const parts: Array<string | null> = [];
  parts.push(`status ${args.sessionKey ?? "unknown"}`);

  const modelLabel = model ? `${provider}/${model}` : "unknown";
  const authLabel = authMode && authMode !== "unknown" ? ` (${authMode})` : "";
  parts.push(`model ${modelLabel}${authLabel}`);

  const usagePair = formatUsagePair(inputTokens, outputTokens);
  if (usagePair) parts.push(usagePair);
  if (costLabel) parts.push(`cost ${costLabel}`);

  const contextSummary = formatContextUsageShort(
    totalTokens && totalTokens > 0 ? totalTokens : null,
    contextTokens ?? null,
  );
  parts.push(contextSummary);
  parts.push(`compactions ${entry?.compactionCount ?? 0}`);
  parts.push(`think ${thinkLevel}`);
  parts.push(`verbose ${verboseLevel}`);
  parts.push(`reasoning ${reasoningLevel}`);
  parts.push(`elevated ${elevatedLevel}`);
  if (groupActivationValue) parts.push(`activation ${groupActivationValue}`);

  const queueMode = args.queue?.mode ?? "unknown";
  const queueDetails = formatQueueDetails(args.queue);
  parts.push(`queue ${queueMode}${queueDetails}`);

  if (args.usageLine) parts.push(args.usageLine);

  return parts.filter(Boolean).join(" · ");
}

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> | /cost on|off",
    "More: /commands for all slash commands"
  ].join("\n");
}

export function buildCommandsMessage(): string {
  const lines = ["ℹ️ Slash commands"];
  for (const command of listChatCommands()) {
    const primary = `/${command.nativeName}`;
    const seen = new Set<string>();
    const aliases = command.textAliases
      .map((alias) => alias.trim())
      .filter(Boolean)
      .filter((alias) => alias.toLowerCase() !== primary.toLowerCase())
      .filter((alias) => {
        const key = alias.toLowerCase();
        if (seen.has(key)) return false;
        seen.add(key);
        return true;
      });
    const aliasLabel = aliases.length
      ? ` (aliases: ${aliases.join(", ")})`
      : "";
    const scopeLabel = command.supportsNative === false ? " (text-only)" : "";
    lines.push(`${primary}${aliasLabel}${scopeLabel} - ${command.description}`);
  }
  return lines.join("\n");
}