import re
import logging

from langchain.agents.middleware import AgentMiddleware
from langchain.tools.tool_node import ToolCallRequest

logger = logging.getLogger('app')

# Common file extensions in lowercase, used for regex matching.
_FILE_EXT = (
    # Documents
    r'txt|pdf|doc|docx|xls|xlsx|ppt|pptx|csv|md|rtf|odt|ods|odp'
    r'|jtd|jtt|jaw'  # JustSystems Ichitaro
    # Images
    r'|jpg|jpeg|png|gif|bmp|svg|webp|ico|tiff|tif'
    # Audio
    r'|mp3|wav|ogg|flac|aac|m4a'
    # Video
    r'|mp4|avi|mov|mkv|wmv|flv|webm'
    # Archives
    r'|zip|tar|gz|bz2|rar|7z|tgz'
    # Code / data
    r'|py|js|ts|html|htm|css|json|xml|yaml|yml|sql|sh|bat'
    r'|java|c|cpp|h|rb|go|rs|php'
    # Others
    r'|log|ini|cfg|conf|toml|env|bin|exe|dmg|iso|db|sqlite|tmp|bak'
)

_EXT_PATTERN = rf'\.(?:{_FILE_EXT})\b'

# Anchor: file extension or directory separator /, used to match directory names in the middle of a path.
_ANCHOR = rf'(?:{_EXT_PATTERN}|/)'

# Pattern 1: CJK character + spaces + (segment starting with alphanumeric + anchor)
# "農作業 2025.jtd" → "農業2025.jtd"
# "ファイル report.txt" → "ファイルreport.txt"
# "/datasets/報告書 2025/file.txt" → "/datasets/報告書2025/file.txt"
_CJK_TO_ALNUM = re.compile(
    rf'([\u4e00-\u9fff\u3040-\u309f\u30a0-\u30ff])\s+([a-zA-Z0-9][\w]*{_ANCHOR})'
)

# Pattern 2: digits + spaces + (segment starting with CJK + anchor)
# "2025 報告書.txt" → "2025報告書.txt"
# "/datasets/2025 報告書/file.txt" → "/datasets/2025報告書/file.txt"
# Note: only match digits, not letters, to avoid incorrectly rewriting "cat 報告.txt".
# Note: (?<!\.) excludes false matches across arguments like "xxx.py ファイル.txt".
_ALNUM_TO_CJK = re.compile(
    rf'(?<!\.)(\d+)\s+([\u4e00-\u9fff\u3040-\u309f\u30a0-\u30ff][\w]*{_ANCHOR})'
)

# Pattern 3: in path context (after /), letters + spaces + (alphanumeric segment + anchor)
# "/data/report 2025年度.xlsx" → "/data/report2025年度.xlsx"
# Use (?<=/) so it only applies inside paths and avoids rewriting "cat report 2025.txt".
_PATH_LETTER = re.compile(
    rf'(?<=/)([a-zA-Z][\w]*)\s+([a-zA-Z0-9][\w]*{_ANCHOR})'
)


def fix_filename_spacing(text: str) -> str:
    """Fix extra spaces around CJK/non-CJK boundaries in file names and paths until stable."""
    prev = None
    while prev != text:
        prev = text
        text = _CJK_TO_ALNUM.sub(r'\1\2', text)
        text = _ALNUM_TO_CJK.sub(r'\1\2', text)
        text = _PATH_LETTER.sub(r'\1\2', text)
    return text


class FilePathFixMiddleware(AgentMiddleware):
    """Fix extra spaces in CJK file names and paths inside tool call arguments."""

    def _fix_tool_call_args(self, request: ToolCallRequest) -> None:
        args = request.tool_call.get('args', {})
        for key, value in args.items():
            if isinstance(value, str):
                fixed = fix_filename_spacing(value)
                if fixed != value:
                    logger.info(f"Filename spacing fix: args['{key}'] '{value}' -> '{fixed}'")
                    args[key] = fixed

    def wrap_tool_call(self, request, handler):
        self._fix_tool_call_args(request)
        return handler(request)

    async def awrap_tool_call(self, request, handler):
        self._fix_tool_call_args(request)
        return await handler(request)