from __future__ import annotations

import hashlib
import json
import os
import subprocess
import tempfile
from datetime import datetime, timezone
from functools import lru_cache
from pathlib import Path
from typing import Any, Iterable, Iterator


START_MARKER = "<!-- auto-preference-learner:start -->"
END_MARKER = "<!-- auto-preference-learner:end -->"
STATE_DIR_NAME = "auto-preference-learner"


def codex_home(value: str | None = None) -> Path:
    raw = value or os.environ.get("CODEX_HOME")
    return Path(raw).expanduser().resolve() if raw else (Path.home() / ".codex").resolve()


def utc_now() -> datetime:
    return datetime.now(timezone.utc)


def isoformat(value: datetime | None = None) -> str:
    return (value or utc_now()).astimezone(timezone.utc).isoformat().replace("+00:00", "Z")


def parse_timestamp(value: Any) -> datetime | None:
    if isinstance(value, (int, float)):
        try:
            return datetime.fromtimestamp(float(value), tz=timezone.utc)
        except (OverflowError, OSError, ValueError):
            return None
    if not isinstance(value, str) or not value.strip():
        return None
    text = value.strip()
    if text.endswith("Z"):
        text = text[:-1] + "+00:00"
    try:
        parsed = datetime.fromisoformat(text)
    except ValueError:
        return None
    if parsed.tzinfo is None:
        parsed = parsed.replace(tzinfo=timezone.utc)
    return parsed.astimezone(timezone.utc)


def read_jsonl(path: Path) -> Iterator[tuple[int, dict[str, Any]]]:
    with path.open("r", encoding="utf-8-sig", errors="replace") as handle:
        for line_number, line in enumerate(handle, 1):
            if not line.strip():
                continue
            try:
                value = json.loads(line)
            except json.JSONDecodeError:
                continue
            if isinstance(value, dict):
                yield line_number, value


def extract_text(value: Any) -> str:
    if isinstance(value, str):
        return value.strip()
    if isinstance(value, list):
        parts: list[str] = []
        for item in value:
            if isinstance(item, str):
                parts.append(item)
            elif isinstance(item, dict):
                kind = item.get("type")
                if kind in {"text", "input_text", "output_text"} or "text" in item:
                    text = item.get("text")
                    if isinstance(text, str):
                        parts.append(text)
        return "\n".join(part.strip() for part in parts if part.strip()).strip()
    if isinstance(value, dict):
        for key in ("text", "message", "content"):
            text = extract_text(value.get(key))
            if text:
                return text
    return ""


def sha256_bytes(value: bytes) -> str:
    return hashlib.sha256(value).hexdigest()


def stable_id(*parts: str, prefix: str = "") -> str:
    digest = hashlib.sha256("\0".join(parts).encode("utf-8")).hexdigest()[:16]
    return f"{prefix}{digest}"


def load_json(path: Path, default: Any) -> Any:
    if not path.exists():
        return default
    with path.open("r", encoding="utf-8-sig") as handle:
        return json.load(handle)


def atomic_write_text(path: Path, content: str) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    descriptor, temporary = tempfile.mkstemp(prefix=f".{path.name}.", suffix=".tmp", dir=path.parent)
    try:
        with os.fdopen(descriptor, "w", encoding="utf-8", newline="") as handle:
            handle.write(content)
            handle.flush()
            os.fsync(handle.fileno())
        os.replace(temporary, path)
    except BaseException:
        try:
            os.unlink(temporary)
        except FileNotFoundError:
            pass
        raise


def atomic_write_bytes(path: Path, content: bytes) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    descriptor, temporary = tempfile.mkstemp(prefix=f".{path.name}.", suffix=".tmp", dir=path.parent)
    try:
        with os.fdopen(descriptor, "wb") as handle:
            handle.write(content)
            handle.flush()
            os.fsync(handle.fileno())
        os.replace(temporary, path)
    except BaseException:
        try:
            os.unlink(temporary)
        except FileNotFoundError:
            pass
        raise


def atomic_write_json(path: Path, value: Any) -> None:
    atomic_write_text(path, json.dumps(value, ensure_ascii=False, indent=2) + "\n")


def write_json_output(value: Any, output: str | None) -> None:
    text = json.dumps(value, ensure_ascii=False, indent=2) + "\n"
    if output:
        atomic_write_text(Path(output).expanduser().resolve(), text)
    else:
        print(text, end="")


def find_git_root(cwd: Path) -> Path | None:
    if not cwd.is_dir():
        return None
    result = subprocess.run(
        ["git", "-C", str(cwd), "rev-parse", "--show-toplevel"],
        capture_output=True,
        text=True,
        encoding="utf-8",
        errors="replace",
        check=False,
    )
    if result.returncode != 0 or not result.stdout.strip():
        return None
    return Path(result.stdout.strip()).resolve()


@lru_cache(maxsize=4096)
def project_root_for_cwd(value: str | None) -> Path | None:
    if not value:
        return None
    try:
        cwd = Path(value).expanduser().resolve()
    except (OSError, RuntimeError):
        return None
    return find_git_root(cwd) or (cwd if cwd.is_dir() else None)


def normalize_text(value: str) -> str:
    return " ".join(value.split()).casefold()


def iter_dicts(value: Any) -> Iterable[dict[str, Any]]:
    if isinstance(value, dict):
        yield value
        for child in value.values():
            yield from iter_dicts(child)
    elif isinstance(value, list):
        for child in value:
            yield from iter_dicts(child)