import type { AssistantMessage } from "@mariozechner/pi-ai";
import { sanitizeUserFacingText } from "./pi-embedded-helpers.js";
import { formatToolDetail, resolveToolDisplay } from "./tool-display.js";

/**
 * Strip malformed Minimax tool invocations that leak into text content.
 * Minimax sometimes embeds tool calls as XML in text blocks instead of
 * proper structured tool calls. This removes:
 * - <invoke name="...">...</invoke> blocks
 * - </minimax:tool_call> closing tags
 */
function stripMinimaxToolCallXml(text: string): string {
  if (!text) return text;
  if (!/minimax:tool_call/i.test(text)) return text;

  // Remove <invoke ...>...</invoke> blocks (non-greedy to handle multiple).
  let cleaned = text.replace(/<invoke\b[^>]*>[\s\S]*?<\/invoke>/gi, "");

  // Remove stray minimax tool tags.
  cleaned = cleaned.replace(/<\/?minimax:tool_call>/gi, "");

  return cleaned;
}

/**
 * Strip downgraded tool call text representations that leak into text content.
 * When replaying history to Gemini, tool calls without `thought_signature` are
 * downgraded to text blocks like `[Tool Call: name (ID: ...)]`. These should
 * not be shown to users.
 */
function stripDowngradedToolCallText(text: string): string {
  if (!text) return text;
  if (!/\[Tool (?:Call|Result)/i.test(text)) return text;

  const consumeJsonish = (
    input: string,
    start: number,
    options?: { allowLeadingNewlines?: boolean },
  ): number | null => {
    const { allowLeadingNewlines = false } = options ?? {};
    let index = start;
    while (index < input.length) {
      const ch = input[index];
      if (ch === " " || ch === "\t") {
        index += 1;
        continue;
      }
      if (allowLeadingNewlines && (ch === "\n" || ch === "\r")) {
        index += 1;
        continue;
      }
      break;
    }
    if (index >= input.length) return null;

    const startChar = input[index];
    if (startChar === "{" || startChar === "[") {
      let depth = 0;
      let inString = false;
      let escape = false;
      for (let i = index; i < input.length; i += 1) {
        const ch = input[i];
        if (inString) {
          if (escape) {
            escape = false;
          } else if (ch === "\\") {
            escape = true;
          } else if (ch === '"') {
            inString = false;
          }
          continue;
        }
        if (ch === '"') {
          inString = true;
          continue;
        }
        if (ch === "{" || ch === "[") {
          depth += 1;
          continue;
        }
        if (ch === "}" || ch === "]") {
          depth -= 1;
          if (depth === 0) return i + 1;
        }
      }
      return null;
    }

    if (startChar === '"') {
      let escape = false;
      for (let i = index + 1; i < input.length; i += 1) {
        const ch = input[i];
        if (escape) {
          escape = false;
          continue;
        }
        if (ch === "\\") {
          escape = true;
          continue;
        }
        if (ch === '"') return i + 1;
      }
      return null;
    }

    let end = index;
    while (end < input.length && input[end] !== "\n" && input[end] !== "\r") {
      end += 1;
    }
    return end;
  };

  const stripToolCalls = (input: string): string => {
    const markerRe = /\[Tool Call:[^\]]*\]/gi;
    let result = "";
    let cursor = 0;
    for (const match of input.matchAll(markerRe)) {
      const start = match.index ?? 0;
      if (start < cursor) continue;
      result += input.slice(cursor, start);
      let index = start + match[0].length;
      while (index < input.length && (input[index] === " " || input[index] === "\t")) {
        index += 1;
      }
      if (input[index] === "\r") {
        index += 1;
        if (input[index] === "\n") index += 1;
      } else if (input[index] === "\n") {
        index += 1;
      }
      while (index < input.length && (input[index] === " " || input[index] === "\t")) {
        index += 1;
      }
      if (input.slice(index, index + 9).toLowerCase() === "arguments") {
        index += 9;
        if (input[index] === ":") index += 1;
        if (input[index] === " ") index += 1;
        const end = consumeJsonish(input, index, { allowLeadingNewlines: true });
        if (end !== null) index = end;
      }
      if (
        (input[index] === "\n" || input[index] === "\r") &&
        (result.endsWith("\n") || result.endsWith("\r") || result.length === 0)
      ) {
        if (input[index] === "\r") index += 1;
        if (input[index] === "\n") index += 1;
      }
      cursor = index;
    }
    result += input.slice(cursor);
    return result;
  };

  // Remove [Tool Call: name (ID: ...)] blocks and their Arguments.
  let cleaned = stripToolCalls(text);

  // Remove [Tool Result for ID ...] blocks and their content.
  cleaned = cleaned.replace(/\[Tool Result for ID[^\]]*\]\n?[\s\S]*?(?=\n*\[Tool |\n*$)/gi, "");

  return cleaned.trim();
}

/**
 * Strip thinking tags and their content from text.
 * This is a safety net for cases where the model outputs <think> tags
 * that slip through other filtering mechanisms.
 */
function stripThinkingTagsFromText(text: string): string {
  if (!text) return text;
  // Quick check to avoid regex overhead when no tags present.
  if (!/(?:think(?:ing)?|thought|antthinking)/i.test(text)) return text;

  const tagRe = /<\s*(\/?)\s*(?:think(?:ing)?|thought|antthinking)\b[^>]*>/gi;
  let result = "";
  let lastIndex = 0;
  let inThinking = false;

  for (const match of text.matchAll(tagRe)) {
    const idx = match.index ?? 0;
    const isClose = match[1] === "/";

    if (!inThinking && !isClose) {
      // Opening tag - save text before it.
      result += text.slice(lastIndex, idx);
      inThinking = true;
    } else if (inThinking && isClose) {
      // Closing tag - skip content inside.
      inThinking = false;
    }
    lastIndex = idx + match[0].length;
  }

  // Append remaining text if we're not inside thinking.
  if (!inThinking) {
    result += text.slice(lastIndex);
  }

  return result.trim();
}

export function extractAssistantText(msg: AssistantMessage): string {
  const isTextBlock = (block: unknown): block is { type: "text"; text: string } => {
    if (!block || typeof block !== "object") return false;
    const rec = block as Record<string, unknown>;
    return rec.type === "text" && typeof rec.text === "string";
  };

  const blocks = Array.isArray(msg.content)
    ? msg.content
        .filter(isTextBlock)
        .map((c) =>
          stripThinkingTagsFromText(
            stripDowngradedToolCallText(stripMinimaxToolCallXml(c.text)),
          ).trim(),
        )
        .filter(Boolean)
    : [];
  const extracted = blocks.join("\n").trim();
  return sanitizeUserFacingText(extracted);
}

export function extractAssistantThinking(msg: AssistantMessage): string {
  if (!Array.isArray(msg.content)) return "";
  const blocks = msg.content
    .map((block) => {
      if (!block || typeof block !== "object") return "";
      const record = block as unknown as Record<string, unknown>;
      if (record.type === "thinking" && typeof record.thinking === "string") {
        return record.thinking.trim();
      }
      return "";
    })
    .filter(Boolean);
  return blocks.join("\n").trim();
}

export function formatReasoningMessage(text: string): string {
  const trimmed = text.trim();
  if (!trimmed) return "";
  // Show reasoning in italics (cursive) for markdown-friendly surfaces (Discord, etc.).
  // Keep the plain "Reasoning:" prefix so existing parsing/detection keeps working.
  return `Reasoning:\n_${trimmed}_`;
}

type ThinkTaggedSplitBlock =
  | { type: "thinking"; thinking: string }
  | { type: "text"; text: string };

export function splitThinkingTaggedText(text: string): ThinkTaggedSplitBlock[] | null {
  const trimmedStart = text.trimStart();
  // Avoid false positives: only treat it as structured thinking when it begins
  // with a think tag (common for local/OpenAI-compat providers that emulate
  // reasoning blocks via tags).
  if (!trimmedStart.startsWith("<")) return null;
  const openRe = /<\s*(?:think(?:ing)?|thought|antthinking)\s*>/i;
  const closeRe = /<\s*\/\s*(?:think(?:ing)?|thought|antthinking)\s*>/i;
  if (!openRe.test(trimmedStart)) return null;
  if (!closeRe.test(text)) return null;

  const scanRe = /<\s*(\/?)\s*(?:think(?:ing)?|thought|antthinking)\s*>/gi;
  let inThinking = false;
  let cursor = 0;
  let thinkingStart = 0;
  const blocks: ThinkTaggedSplitBlock[] = [];

  const pushText = (value: string) => {
    if (!value) return;
    blocks.push({ type: "text", text: value });
  };
  const pushThinking = (value: string) => {
    const cleaned = value.trim();
    if (!cleaned) return;
    blocks.push({ type: "thinking", thinking: cleaned });
  };

  for (const match of text.matchAll(scanRe)) {
    const index = match.index ?? 0;
    const isClose = Boolean(match[1]?.includes("/"));

    if (!inThinking && !isClose) {
      pushText(text.slice(cursor, index));
      thinkingStart = index + match[0].length;
      inThinking = true;
      continue;
    }

    if (inThinking && isClose) {
      pushThinking(text.slice(thinkingStart, index));
      cursor = index + match[0].length;
      inThinking = false;
    }
  }

  if (inThinking) return null;
  pushText(text.slice(cursor));

  const hasThinking = blocks.some((b) => b.type === "thinking");
  if (!hasThinking) return null;
  return blocks;
}

export function promoteThinkingTagsToBlocks(message: AssistantMessage): void {
  if (!Array.isArray(message.content)) return;
  const hasThinkingBlock = message.content.some((block) => block.type === "thinking");
  if (hasThinkingBlock) return;

  const next: AssistantMessage["content"] = [];
  let changed = false;

  for (const block of message.content) {
    if (block.type !== "text") {
      next.push(block);
      continue;
    }
    const split = splitThinkingTaggedText(block.text);
    if (!split) {
      next.push(block);
      continue;
    }
    changed = true;
    for (const part of split) {
      if (part.type === "thinking") {
        next.push({ type: "thinking", thinking: part.thinking });
      } else if (part.type === "text") {
        const cleaned = part.text.trimStart();
        if (cleaned) next.push({ type: "text", text: cleaned });
      }
    }
  }

  if (!changed) return;
  message.content = next;
}

export function extractThinkingFromTaggedText(text: string): string {
  if (!text) return "";
  const scanRe = /<\s*(\/?)\s*(?:think(?:ing)?|thought|antthinking)\s*>/gi;
  let result = "";
  let lastIndex = 0;
  let inThinking = false;
  for (const match of text.matchAll(scanRe)) {
    const idx = match.index ?? 0;
    if (inThinking) {
      result += text.slice(lastIndex, idx);
    }
    const isClose = match[1] === "/";
    inThinking = !isClose;
    lastIndex = idx + match[0].length;
  }
  return result.trim();
}

export function extractThinkingFromTaggedStream(text: string): string {
  if (!text) return "";
  const closed = extractThinkingFromTaggedText(text);
  if (closed) return closed;

  const openRe = /<\s*(?:think(?:ing)?|thought|antthinking)\s*>/gi;
  const closeRe = /<\s*\/\s*(?:think(?:ing)?|thought|antthinking)\s*>/gi;
  const openMatches = [...text.matchAll(openRe)];
  if (openMatches.length === 0) return "";
  const closeMatches = [...text.matchAll(closeRe)];
  const lastOpen = openMatches[openMatches.length - 1];
  const lastClose = closeMatches[closeMatches.length - 1];
  if (lastClose && (lastClose.index ?? -1) > (lastOpen.index ?? -1)) {
    return closed;
  }
  const start = (lastOpen.index ?? 0) + lastOpen[0].length;
  return text.slice(start).trim();
}

export function inferToolMetaFromArgs(toolName: string, args: unknown): string | undefined {
  const display = resolveToolDisplay({ name: toolName, args });
  return formatToolDetail(display);
}