#!/usr/bin/env python3
"""Migrate Microdot controllers to native FastAPI (no compat layer)."""

from __future__ import annotations

import re
import sys
from pathlib import Path

CONTROLLERS = Path(__file__).resolve().parents[1] / "src" / "controllers"

IMPORT_BLOCK = """from fastapi import APIRouter, Request
from http_responses import J, html_response, plain, read_json, send_file
from http_session import with_session

"""

_JSON_HEADERS = re.compile(
    r"return json\.dumps\(([\s\S]*?)\),\s*(\d+)\s*,\s*\{\s*"
    r"['\"]Content-Type['\"]\s*:\s*['\"]application/json['\"]\s*,?\s*\}",
    re.MULTILINE,
)

_JSON_PLAIN = re.compile(
    r"^(\s*)return json\.dumps\((.+)\),\s*(\d+)\s*$",
    re.MULTILINE,
)

_HTML_LINE = re.compile(
    r"^(\s*)return ([^,\n]+),\s*(\d+),\s*\{['\"]Content-Type['\"]: ['\"]text/html['\"]\}\s*$",
    re.MULTILINE,
)

_PLAIN_LINE = re.compile(
    r"^(\s*)return ([^,\n]+),\s*(\d+),\s*\{['\"]Content-Type['\"]: ['\"]text/plain[^'\"]*['\"]\}\s*$",
    re.MULTILINE,
)

_PAREN_JSON = re.compile(
    r"return \(\s*json\.dumps\(([\s\S]*?)\)\s*,\s*(\d+)\s*,\s*"
    r"\{['\"]Content-Type['\"]: ['\"]application/json['\"]\}\s*,?\s*\)",
    re.MULTILINE,
)

_PAREN_JSON_NOHDR = re.compile(
    r"return \(\s*json\.dumps\(([\s\S]*?)\)\s*,\s*(\d+)\s*,?\s*\)",
    re.MULTILINE,
)

_PAREN_HTML = re.compile(
    r"return \(\s*([^,]+?)\s*,\s*(\d+)\s*,\s*"
    r"\{['\"]Content-Type['\"]: ['\"]text/html['\"]\}\s*,?\s*\)",
    re.DOTALL,
)


def _insert_imports(text: str) -> str:
    if "from fastapi import APIRouter" in text:
        return text
    fut = re.search(r"^from __future__ import annotations\n", text, re.M)
    if fut:
        return text[: fut.end()] + "\n" + IMPORT_BLOCK + text[fut.end() :]
    doc = re.match(r'("""[\s\S]*?"""\n+|\'\'\'[\s\S]*?\'\'\'\n+)', text)
    if doc:
        return text[: doc.end()] + "\n" + IMPORT_BLOCK + text[doc.end() :]
    return IMPORT_BLOCK + text


def _strip_microdot(text: str) -> str:
    text = re.sub(r"from microdot import Microdot(?:, send_file)?\n", "", text)
    text = re.sub(r"from microdot\.session import with_session\n", "", text)
    text = re.sub(r"from microdot import send_file\n", "", text)
    text = text.replace("controller = Microdot()", "router = APIRouter()")
    text = text.replace("@controller.", "@router.")
    return text


def _convert_paths(text: str) -> str:
    def fix(m: re.Match) -> str:
        method, path = m.group(1), m.group(2)
        if path == "":
            path = "/"
        path = re.sub(r"<(\w+)>", r"{\1}", path)
        return f'@router.{method}("{path}")'

    return re.sub(
        r"@router\.(get|post|put|delete|patch)\(['\"]([^'\"]*)['\"]\)",
        fix,
        text,
    )


def _convert_request_access(text: str) -> str:
    text = text.replace("request.json or {}", "await read_json(request)")
    text = re.sub(r"(?<![.\w])request\.json(?!\w)", "await read_json(request)", text)
    text = text.replace("request.args.get", "request.query_params.get")
    return text


def _convert_request_annotations(text: str) -> str:
    text = re.sub(r"async def (\w+)\(request,", r"async def \1(request: Request,", text)
    text = re.sub(r"async def (\w+)\(request\)", r"async def \1(request: Request)", text)
    return text


def _convert_returns(text: str) -> str:
    text = _PAREN_JSON.sub(r"return J(\1, \2)", text)
    text = _PAREN_JSON_NOHDR.sub(r"return J(\1, \2)", text)
    text = _PAREN_HTML.sub(r"return html_response(\1, \2)", text)
    text = _JSON_HEADERS.sub(r"return J(\1, \2)", text)
    text = _JSON_PLAIN.sub(r"\1return J(\2, \3)", text)
    text = _HTML_LINE.sub(r"\1return html_response(\2, \3)", text)
    text = _PLAIN_LINE.sub(r"\1return plain(\2, \3)", text)
    text = re.sub(
        r'^(\s*)return "([^"]+)",\s*(\d+)\s*$',
        r'\1return plain("\2", \3)',
        text,
        flags=re.MULTILINE,
    )
    return text


def convert_file(path: Path) -> str:
    text = path.read_text(encoding="utf-8")
    if "Microdot" not in text:
        return text
    text = _strip_microdot(text)
    text = _insert_imports(text)
    text = _convert_paths(text)
    text = _convert_request_access(text)
    text = _convert_request_annotations(text)
    text = _convert_returns(text)
    return text


def main() -> int:
    for path in sorted(CONTROLLERS.glob("*.py")):
        if path.name == "__init__.py":
            continue
        path.write_text(convert_file(path), encoding="utf-8")
        print(path.name)
    return 0


if __name__ == "__main__":
    sys.exit(main())