from __future__ import annotations

import re
import socket
import uuid
from dataclasses import dataclass
from pathlib import Path
from typing import Any

import yaml

from api.models.managed_repo import ManagedRepo


_TASK_BLOCK_RE = re.compile(r"```task\s*\n(.*?)\n```", re.DOTALL)


@dataclass(frozen=True)
class WorkplanFileRef:
    repo_path: Path
    path: Path
    archived: bool

    @property
    def relative_path(self) -> str:
        return str(self.path.relative_to(self.repo_path))


def resolve_repo_path(repo: ManagedRepo | None) -> Path | None:
    if repo is None:
        return None
    hostname = socket.gethostname()
    host_paths = repo.host_paths or {}
    candidates = [host_paths.get(hostname), repo.local_path]
    for raw in candidates:
        if not raw:
            continue
        path = Path(raw).expanduser()
        if path.is_dir():
            return path
    return None


def find_workplan_for_workstream(
    repo: ManagedRepo | None,
    workstream_id: uuid.UUID,
) -> WorkplanFileRef | None:
    repo_path = resolve_repo_path(repo)
    if repo_path is None:
        return None
    workplans_dir = repo_path / "workplans"
    for directory, archived in (
        (workplans_dir, False),
        (workplans_dir / "archived", True),
    ):
        if not directory.is_dir():
            continue
        for path in sorted(directory.glob("*.md")):
            meta = _frontmatter(path)
            if str(meta.get("state_hub_workstream_id", "")).strip().strip('"') == str(workstream_id):
                return WorkplanFileRef(repo_path=repo_path, path=path, archived=archived)
    return None


def task_block_linked(path: Path, task_id: uuid.UUID) -> bool:
    return _task_block_for_task(path, task_id) is not None


def workplan_status(path: Path) -> str | None:
    status = _frontmatter(path).get("status")
    return str(status).strip() if status is not None else None


def task_block_status(path: Path, task_id: uuid.UUID) -> str | None:
    meta = _task_block_for_task(path, task_id)
    if meta is None:
        return None
    status = meta.get("status")
    return str(status).strip() if status is not None else None


def patch_workplan_status(path: Path, status: str) -> bool:
    return _patch_frontmatter_field(path, "status", status)


def patch_task_status(path: Path, task_id: uuid.UUID, status: str) -> bool:
    text = path.read_text(encoding="utf-8")

    def _replace(match: re.Match) -> str:
        block = match.group(0)
        meta = _parse_task_block(match.group(1))
        if str(meta.get("state_hub_task_id", "")).strip().strip('"') != str(task_id):
            return block
        replaced = re.sub(
            r"^(status:\s*)\S+",
            rf"\g<1>{status}",
            block,
            count=1,
            flags=re.MULTILINE,
        )
        if replaced != block:
            return replaced
        return block.replace("\n```", f"\nstatus: {status}\n```", 1)

    new_text = _TASK_BLOCK_RE.sub(_replace, text)
    if new_text == text:
        return False
    path.write_text(new_text, encoding="utf-8")
    return True


def _frontmatter(path: Path) -> dict[str, Any]:
    try:
        text = path.read_text(encoding="utf-8")
    except OSError:
        return {}
    if not text.startswith("---"):
        return {}
    parts = text.split("---", 2)
    if len(parts) < 3:
        return {}
    try:
        return yaml.safe_load(parts[1].strip()) or {}
    except yaml.YAMLError:
        return {}


def _patch_frontmatter_field(path: Path, key: str, value: str) -> bool:
    text = path.read_text(encoding="utf-8")
    if not text.startswith("---"):
        return False
    lines = text.split("\n")
    close_idx = None
    for i, line in enumerate(lines[1:], 1):
        if line.strip() == "---":
            close_idx = i
            break
    if close_idx is None:
        return False

    new_line = f"{key}: {value}"
    for i in range(1, close_idx):
        if re.match(rf"^\s*{re.escape(key)}\s*:", lines[i]):
            if lines[i] == new_line:
                return False
            lines[i] = new_line
            path.write_text("\n".join(lines), encoding="utf-8")
            return True

    lines.insert(close_idx, new_line)
    path.write_text("\n".join(lines), encoding="utf-8")
    return True


def _task_block_for_task(path: Path, task_id: uuid.UUID) -> dict[str, Any] | None:
    try:
        text = path.read_text(encoding="utf-8")
    except OSError:
        return None
    for match in _TASK_BLOCK_RE.finditer(text):
        meta = _parse_task_block(match.group(1))
        if str(meta.get("state_hub_task_id", "")).strip().strip('"') == str(task_id):
            return meta
    return None


def _parse_task_block(raw: str) -> dict[str, Any]:
    try:
        return yaml.safe_load(raw.strip()) or {}
    except yaml.YAMLError:
        return {}