// SPDX-License-Identifier: AGPL-3.0-only
// Copyright 2026-present the Unsloth AI Inc. team. All rights reserved.
// Ported from studio/backend/core/inference/tool_call_parser.py.
// Original: https://github.com/unslothai/unsloth/blob/main/studio/backend/core/inference/tool_call_parser.py

// ── Constants ────────────────────────────────────────────────────────────

export const XML_TOOL_OPEN = '<tool_call>';
export const XML_TOOL_CLOSE = '</tool_call>';
export const INVOKE_TOOL_OPEN = '<invoke';
export const INVOKE_TOOL_CLOSE = '</invoke>';

export const TOOL_XML_SIGNALS = [XML_TOOL_OPEN, '<function=', INVOKE_TOOL_OPEN] as const;

export const TOOL_ERROR_PREFIXES = [
  'Error',
  'Search failed',
  'Execution error',
  'Blocked:',
  'Exit code',
  'Failed to fetch',
  'Failed to resolve',
  'No query provided',
] as const;

export const DUPLICATE_CALL_NUDGE =
  'You already made this exact call. Do not repeat the same tool ' +
  'call. Try a different approach: fetch a URL from previous ' +
  'results, use Python to process data you already have, or ' +
  'provide your final answer now.';

export const TOOL_ERROR_NUDGE =
  '\n\nThe tool call encountered an issue. Please try a different ' +
  'approach or rephrase your request.';

export const BUDGET_EXHAUSTED_NUDGE =
  'You have used all available tool calls. Based on everything you ' +
  'have found so far, provide your final answer now. Do not call ' +
  'any more tools.';

// ── Strip patterns ───────────────────────────────────────────────────────

const TOOL_CLOSED_PATS = [
  /<tool_call>.*?<\/tool_call>/gs,
  /<function=\w+>.*?<\/function>/gs,
  /<invoke\s[^>]*>.*?<\/invoke>/gs,
];

const TOOL_ALL_PATS = [
  ...TOOL_CLOSED_PATS,
  /<tool_call>.*$/gs,
  /<function=\w+>.*$/gs,
  /<invoke\s[^>]*>.*$/gs,
];

// ── Strip / signal ───────────────────────────────────────────────────────

export function stripToolMarkup(text: string, opts?: { final?: boolean }): string {
  const pats = opts?.final ? TOOL_ALL_PATS : TOOL_CLOSED_PATS;
  for (const pat of pats) {
    text = text.replace(pat, '');
  }
  return opts?.final ? text.trim() : text;
}

export function hasToolSignal(text: string): boolean {
  return TOOL_XML_SIGNALS.some((s) => text.includes(s));
}

// ── parseToolCallsFromText (Unsloth port + Anthropic extension) ──────────

export interface OpenAiToolCall {
  id: string;
  type: 'function';
  function: { name: string; arguments: string };
}

const TC_JSON_START_RE = /<tool_call>\s*\{/g;
const TC_FUNC_START_RE = /<function=(\w+)>\s*/g;
const TC_END_TAG_RE = /<\/tool_call>/;
const TC_FUNC_CLOSE_RE = /\s*<\/function>\s*$/;
const TC_PARAM_START_RE = /<parameter=(\w+)>\s*/g;
const TC_PARAM_CLOSE_RE = /\s*<\/parameter>\s*$/;

const TC_INVOKE_START_RE = /<invoke\s+name\s*=\s*(?:"([^"]*)"|'([^']*)')\s*>/g;
const TC_INVOKE_CLOSE_RE = /\s*<\/invoke>\s*$/;
const TC_INVOKE_PARAM_RE = /<parameter\s+name\s*=\s*(?:"([^"]*)"|'([^']*)')\s*>/g;
const TC_INVOKE_PARAM_CLOSE_RE = /\s*<\/parameter>\s*$/;

function scanBalancedBraces(content: string, start: number): number {
  let depth = 0;
  let i = start;
  let inString = false;
  while (i < content.length) {
    const ch = content[i]!;
    if (inString) {
      if (ch === '\\' && i + 1 < content.length) {
        i += 2;
        continue;
      }
      if (ch === '"') inString = false;
    } else if (ch === '"') {
      inString = true;
    } else if (ch === '{') {
      depth++;
    } else if (ch === '}') {
      depth--;
      if (depth === 0) return i;
    }
    i++;
  }
  return -1;
}

export function parseToolCallsFromText(
  content: string,
  opts?: { idOffset?: number },
): OpenAiToolCall[] {
  const toolCalls: OpenAiToolCall[] = [];
  const idOffset = opts?.idOffset ?? 0;

  // Pattern 1: <tool_call>{json}</tool_call> -- balanced-brace JSON scanner.
  // Skips braces inside JSON strings so nested objects parse correctly.
  TC_JSON_START_RE.lastIndex = 0;
  let m: RegExpExecArray | null;
  while ((m = TC_JSON_START_RE.exec(content)) !== null) {
    const braceStart = m.index + m[0].length - 1;
    const braceEnd = scanBalancedBraces(content, braceStart);
    if (braceEnd === -1) continue;
    const jsonStr = content.slice(braceStart, braceEnd + 1);
    try {
      const obj = JSON.parse(jsonStr) as Record<string, unknown>;
      const name = typeof obj.name === 'string' ? obj.name : '';
      let args: string;
      const rawArgs = obj.arguments ?? {};
      if (typeof rawArgs === 'string') {
        args = rawArgs;
      } else {
        args = JSON.stringify(rawArgs);
      }
      toolCalls.push({
        id: `call_${idOffset + toolCalls.length}`,
        type: 'function',
        function: { name, arguments: args },
      });
    } catch {
      // malformed JSON -- skip
    }
  }

  // Pattern 2: <function=name><parameter=key>value -- closing tags optional.
  // Body boundary uses </tool_call> or next <function= (not </function>,
  // because code parameter values can contain that literal).
  if (toolCalls.length === 0) {
    TC_FUNC_START_RE.lastIndex = 0;
    const funcStarts: Array<{ match: RegExpExecArray; name: string }> = [];
    while ((m = TC_FUNC_START_RE.exec(content)) !== null) {
      funcStarts.push({ match: m, name: m[1]! });
    }
    for (let idx = 0; idx < funcStarts.length; idx++) {
      const { match: fm, name: funcName } = funcStarts[idx]!;
      const bodyStart = fm.index + fm[0].length;
      const nextFunc = idx + 1 < funcStarts.length
        ? funcStarts[idx + 1]!.match.index
        : content.length;
      const endTag = TC_END_TAG_RE.exec(content.slice(bodyStart));
      let bodyEnd = endTag ? bodyStart + endTag.index : content.length;
      bodyEnd = Math.min(bodyEnd, nextFunc);
      let body = content.slice(bodyStart, bodyEnd);
      body = body.replace(TC_FUNC_CLOSE_RE, '');

      const args: Record<string, string> = {};
      TC_PARAM_START_RE.lastIndex = 0;
      const paramStarts: Array<{ match: RegExpExecArray; name: string }> = [];
      let pm: RegExpExecArray | null;
      while ((pm = TC_PARAM_START_RE.exec(body)) !== null) {
        paramStarts.push({ match: pm, name: pm[1]! });
      }
      if (paramStarts.length === 1) {
        // Single param: take everything to body end so embedded
        // </parameter> in code strings is preserved.
        const p = paramStarts[0]!;
        let val = body.slice(p.match.index + p.match[0].length);
        val = val.replace(TC_PARAM_CLOSE_RE, '');
        args[p.name] = val.trim();
      } else {
        for (let pidx = 0; pidx < paramStarts.length; pidx++) {
          const p = paramStarts[pidx]!;
          const valStart = p.match.index + p.match[0].length;
          const nextParam = pidx + 1 < paramStarts.length
            ? paramStarts[pidx + 1]!.match.index
            : body.length;
          let val = body.slice(valStart, nextParam);
          val = val.replace(TC_PARAM_CLOSE_RE, '');
          args[p.name] = val.trim();
        }
      }

      toolCalls.push({
        id: `call_${idOffset + toolCalls.length}`,
        type: 'function',
        function: { name: funcName, arguments: JSON.stringify(args) },
      });
    }
  }

  // Pattern 3: <invoke name="..."><parameter name="...">value -- Anthropic
  // shape that qwen3.6 drifts to from Claude Code documentation residue.
  // Closing tags optional; same single-param fast path as pattern 2.
  if (toolCalls.length === 0) {
    TC_INVOKE_START_RE.lastIndex = 0;
    const invokeStarts: Array<{ match: RegExpExecArray; name: string }> = [];
    while ((m = TC_INVOKE_START_RE.exec(content)) !== null) {
      const name = (m[1] ?? m[2] ?? '').trim();
      if (name) invokeStarts.push({ match: m, name });
    }
    for (let idx = 0; idx < invokeStarts.length; idx++) {
      const { match: im, name: invokeName } = invokeStarts[idx]!;
      const bodyStart = im.index + im[0].length;
      const nextInvoke = idx + 1 < invokeStarts.length
        ? invokeStarts[idx + 1]!.match.index
        : content.length;
      const closeTag = content.slice(bodyStart).match(/<\/invoke>/);
      let bodyEnd = closeTag ? bodyStart + (closeTag.index ?? 0) : content.length;
      bodyEnd = Math.min(bodyEnd, nextInvoke);
      let body = content.slice(bodyStart, bodyEnd);
      body = body.replace(TC_INVOKE_CLOSE_RE, '');

      const args: Record<string, string> = {};
      TC_INVOKE_PARAM_RE.lastIndex = 0;
      const paramStarts: Array<{ match: RegExpExecArray; name: string }> = [];
      let pm: RegExpExecArray | null;
      while ((pm = TC_INVOKE_PARAM_RE.exec(body)) !== null) {
        const pname = (pm[1] ?? pm[2] ?? '').trim();
        if (pname) paramStarts.push({ match: pm, name: pname });
      }
      if (paramStarts.length === 1) {
        const p = paramStarts[0]!;
        let val = body.slice(p.match.index + p.match[0].length);
        val = val.replace(TC_INVOKE_PARAM_CLOSE_RE, '');
        args[p.name] = val.trim();
      } else {
        for (let pidx = 0; pidx < paramStarts.length; pidx++) {
          const p = paramStarts[pidx]!;
          const valStart = p.match.index + p.match[0].length;
          const nextParam = pidx + 1 < paramStarts.length
            ? paramStarts[pidx + 1]!.match.index
            : body.length;
          let val = body.slice(valStart, nextParam);
          val = val.replace(TC_INVOKE_PARAM_CLOSE_RE, '');
          args[p.name] = val.trim();
        }
      }

      toolCalls.push({
        id: `call_${idOffset + toolCalls.length}`,
        type: 'function',
        function: { name: invokeName, arguments: JSON.stringify(args) },
      });
    }
  }

  return toolCalls;
}

// ── BooCode streaming helpers ────────────────────────────────────────────

export interface ParsedCall {
  name: string;
  args: Record<string, unknown>;
}

const PLACEHOLDER_LITERALS = new Set(['...', 'placeholder', '<path>', '<file>']);
const ANGLE_BRACKET_SENTINEL_RE = /^<[^>]+>$/;

export function isPlaceholderArgValue(value: unknown): boolean {
  if (typeof value !== 'string') return false;
  const trimmed = value.trim();
  if (trimmed === '') return true;
  if (PLACEHOLDER_LITERALS.has(trimmed)) return true;
  if (ANGLE_BRACKET_SENTINEL_RE.test(trimmed)) return true;
  return false;
}

function hasPlaceholderArgs(args: Record<string, unknown>): boolean {
  for (const value of Object.values(args)) {
    if (isPlaceholderArgValue(value)) return true;
  }
  return false;
}

function logRejectedPlaceholder(parsed: ParsedCall): void {
  console.debug(
    { toolName: parsed.name, args: parsed.args },
    'rejected placeholder tool call at parse time',
  );
}

const QWEN_FUNCTION_RE = /<function\s*=\s*([^>\s]+)\s*>/;
const QWEN_PARAM_RE = /<parameter\s*=\s*([^>\s]+)\s*>([\s\S]*?)<\/parameter>/g;

export function parseXmlToolCall(block: string): ParsedCall | null {
  const nameMatch = block.match(QWEN_FUNCTION_RE);
  if (!nameMatch || !nameMatch[1]) return null;
  const name = nameMatch[1].trim();
  if (!name) return null;
  const args: Record<string, unknown> = {};
  for (const m of block.matchAll(QWEN_PARAM_RE)) {
    const key = (m[1] ?? '').trim();
    if (!key) continue;
    const raw = (m[2] ?? '').trim();
    try {
      args[key] = JSON.parse(raw);
    } catch {
      args[key] = raw;
    }
  }
  return { name, args };
}

const INVOKE_NAME_RE =
  /<invoke\s+name\s*=\s*("([^"]*)"|'([^']*)')\s*>/;
const INVOKE_PARAM_RE =
  /<parameter\s+name\s*=\s*("([^"]*)"|'([^']*)')\s*>([\s\S]*?)<\/parameter>/g;

export function parseInvokeToolCall(block: string): ParsedCall | null {
  const nameMatch = block.match(INVOKE_NAME_RE);
  if (!nameMatch) return null;
  const name = (nameMatch[2] ?? nameMatch[3] ?? '').trim();
  if (!name) return null;
  const args: Record<string, unknown> = {};
  for (const m of block.matchAll(INVOKE_PARAM_RE)) {
    const key = ((m[2] ?? m[3] ?? '') as string).trim();
    if (!key) continue;
    const raw = (m[4] ?? '').trim();
    try {
      args[key] = JSON.parse(raw);
    } catch {
      args[key] = raw;
    }
  }
  return { name, args };
}

const ALL_OPENERS = [XML_TOOL_OPEN, INVOKE_TOOL_OPEN] as const;

export function partialXmlOpenerStart(s: string): number {
  let earliest = -1;
  for (const op of ALL_OPENERS) {
    const idx = s.indexOf(op);
    if (idx === -1) continue;
    if (earliest === -1 || idx < earliest) earliest = idx;
  }
  if (earliest !== -1) return earliest;
  const lastLt = s.lastIndexOf('<');
  if (lastLt === -1) return -1;
  const suffix = s.slice(lastLt);
  for (const op of ALL_OPENERS) {
    if (op.startsWith(suffix) && suffix.length < op.length) return lastLt;
  }
  return -1;
}

export interface ToolCallExtraction {
  flushed: string;
  calls: ParsedCall[];
  remaining: string;
}

interface OpenerSpec {
  open: string;
  close: string;
  parse: (block: string) => ParsedCall | null;
}

const OPENER_SPECS: ReadonlyArray<OpenerSpec> = [
  { open: XML_TOOL_OPEN, close: XML_TOOL_CLOSE, parse: parseXmlToolCall },
  { open: INVOKE_TOOL_OPEN, close: INVOKE_TOOL_CLOSE, parse: parseInvokeToolCall },
];

export function extractToolCallBlocks(buffer: string): ToolCallExtraction {
  let flushed = '';
  const calls: ParsedCall[] = [];
  let pos = 0;

  while (pos < buffer.length) {
    let next: { spec: OpenerSpec; openIdx: number; closeIdx: number } | null = null;
    for (const spec of OPENER_SPECS) {
      const openIdx = buffer.indexOf(spec.open, pos);
      if (openIdx === -1) continue;
      const closeIdx = buffer.indexOf(spec.close, openIdx);
      if (closeIdx === -1) continue;
      if (next === null || openIdx < next.openIdx) {
        next = { spec, openIdx, closeIdx };
      }
    }
    if (next === null) break;

    if (next.openIdx > pos) {
      flushed += buffer.slice(pos, next.openIdx);
    }
    const blockEnd = next.closeIdx + next.spec.close.length;
    const block = buffer.slice(next.openIdx, blockEnd);
    const parsed = next.spec.parse(block);
    if (parsed) {
      if (hasPlaceholderArgs(parsed.args)) {
        logRejectedPlaceholder(parsed);
        flushed += block;
      } else {
        calls.push(parsed);
      }
    }
    pos = blockEnd;
  }

  const tail = buffer.slice(pos);
  const partialIdx = partialXmlOpenerStart(tail);
  if (partialIdx === -1) {
    flushed += tail;
    return { flushed, calls, remaining: '' };
  }
  if (partialIdx > 0) {
    flushed += tail.slice(0, partialIdx);
  }
  return { flushed, calls, remaining: tail.slice(partialIdx) };
}