#!/usr/bin/env python3
import re
import sys
from pathlib import Path
from typing import Optional

PLAN_STATUS_START = "<!-- plan-status:start -->"
PLAN_STATUS_END = "<!-- plan-status:end -->"
PLAN_FILE_RE = re.compile(r"^(\d{4}-\d{2}-\d{2})-.+\.md$")
PLAN_LINE_RE = re.compile(
    r"^- \[(?P<check>[ xX])\] `(?P<plan>[^`]+)` (?P<status>done|blocked|pending)(?:: (?P<note>.*))?$"
)
VALID_STATUSES = {"done", "blocked", "pending"}


def usage() -> str:
    return (
        "Usage:\n"
        "  python scripts/plan_progress.py select -plans <dir> -progress <file>\n"
        "  python scripts/plan_progress.py record -plan <path> -status <status> -progress <file> [-note <text>]\n"
        "  python scripts/plan_progress.py -h\n"
        "Options:\n"
        "  -plans DIR\n"
        "  -plan PATH\n"
        "  -status done|blocked|pending\n"
        "  -progress FILE\n"
        "  -note TEXT\n"
        "  -h, -help Show this help.\n"
    )


def parse_flags(args: list[str]) -> dict[str, str]:
    flags: dict[str, str] = {}
    idx = 0
    while idx < len(args):
        arg = args[idx]
        if arg in ("-h", "-help"):
            raise ValueError("help")
        if not arg.startswith("-"):
            raise ValueError(f"unexpected arg: {arg}")
        if idx + 1 >= len(args):
            raise ValueError(f"missing value for {arg}")
        flags[arg] = args[idx + 1]
        idx += 2
    return flags


def normalize_plan_key(plan_value: str) -> str:
    raw = plan_value.strip().replace("\\", "/")
    raw = raw.lstrip("./")
    if raw.startswith("docs/plans/"):
        return raw[len("docs/plans/") :]
    marker = "/docs/plans/"
    if marker in raw:
        return raw.split(marker, 1)[1]
    return raw


def render_plan_line(plan_key: str, status: str, note: Optional[str]) -> str:
    checked = "x" if status == "done" else " "
    if status == "blocked":
        suffix = "blocked"
        if note:
            suffix += f": {note}"
    elif status == "pending":
        suffix = "pending"
    else:
        suffix = "done"
    return f"- [{checked}] `{plan_key}` {suffix}"


def normalize_note(note: str) -> str:
    cleaned = note.replace("\n", " ").replace("\r", " ").replace("`", "'").strip()
    return cleaned


def list_plan_files(plans_dir: Path) -> list[str]:
    entries: list[str] = []
    for path in plans_dir.iterdir():
        if not path.is_file():
            continue
        if not PLAN_FILE_RE.match(path.name):
            continue
        try:
            rel = path.resolve().relative_to(plans_dir.resolve()).as_posix()
        except ValueError:
            rel = path.name
        entries.append(rel)
    return sorted(entries)


def find_block(lines: list[str]) -> Optional[tuple[int, int]]:
    start_idx = None
    for idx, line in enumerate(lines):
        if line.strip() == PLAN_STATUS_START:
            start_idx = idx
            break
    if start_idx is None:
        return None
    for idx in range(start_idx + 1, len(lines)):
        if lines[idx].strip() == PLAN_STATUS_END:
            return start_idx, idx
    return None


def parse_entries(lines: list[str], start_idx: int, end_idx: int) -> list[tuple[str, str, Optional[str], int]]:
    entries: list[tuple[str, str, Optional[str], int]] = []
    for idx in range(start_idx + 1, end_idx):
        line = lines[idx].strip()
        match = PLAN_LINE_RE.match(line)
        if not match:
            continue
        plan_key = normalize_plan_key(match.group("plan"))
        status = match.group("status")
        note = match.group("note")
        entries.append((plan_key, status, note, idx))
    return entries


def render_progress_lines(plans: list[str]) -> list[str]:
    lines = ["# Plan 状态", "", PLAN_STATUS_START]
    for plan_key in plans:
        lines.append(render_plan_line(plan_key, "pending", None))
    lines.append(PLAN_STATUS_END)
    return lines


def select_plan(plans_dir: Path, progress_path: Path) -> tuple[int, str]:
    if not plans_dir.is_dir():
        return 2, f"ERROR: plans dir not found: {plans_dir}"
    plan_keys = list_plan_files(plans_dir)
    if not plan_keys:
        return 2, "ERROR: no plan files found"

    progress_path.parent.mkdir(parents=True, exist_ok=True)
    if progress_path.exists():
        lines = progress_path.read_text(encoding="utf-8").splitlines()
    else:
        lines = []

    block = find_block(lines)
    if not block:
        lines = render_progress_lines(plan_keys)
        progress_path.write_text("\n".join(lines) + "\n", encoding="utf-8")
        return 0, (plans_dir / plan_keys[0]).as_posix()

    start_idx, end_idx = block
    entries = parse_entries(lines, start_idx, end_idx)
    existing = {plan for plan, _, _, _ in entries}
    missing = [plan for plan in plan_keys if plan not in existing]
    if missing:
        insert_lines = [render_plan_line(plan, "pending", None) for plan in missing]
        lines[end_idx:end_idx] = insert_lines
        end_idx += len(insert_lines)
        progress_path.write_text("\n".join(lines) + "\n", encoding="utf-8")
        entries = parse_entries(lines, start_idx, end_idx)

    for plan_key, status, _, _ in entries:
        if status == "pending":
            return 0, (plans_dir / plan_key).as_posix()

    return 2, "ERROR: no pending plans"


def record_status(plan: str, status: str, progress_path: Path, note: Optional[str]) -> tuple[int, str]:
    if status not in VALID_STATUSES:
        return 2, f"ERROR: invalid status: {status}"
    if not plan:
        return 2, "ERROR: plan is required"

    progress_path.parent.mkdir(parents=True, exist_ok=True)
    if progress_path.exists():
        lines = progress_path.read_text(encoding="utf-8").splitlines()
    else:
        lines = []

    plan_key = normalize_plan_key(plan)
    block = find_block(lines)
    if not block:
        lines = render_progress_lines([plan_key])
        block = find_block(lines)
        if not block:
            return 2, "ERROR: failed to create plan status block"

    start_idx, end_idx = block
    entries = parse_entries(lines, start_idx, end_idx)

    rendered_note = None
    if status == "blocked" and note:
        rendered_note = normalize_note(note)

    updated_line = render_plan_line(plan_key, status, rendered_note)
    updated = False
    for entry_plan, _, _, idx in entries:
        if entry_plan == plan_key:
            lines[idx] = updated_line
            updated = True
            break

    if not updated:
        lines[end_idx:end_idx] = [updated_line]

    progress_path.write_text("\n".join(lines) + "\n", encoding="utf-8")
    return 0, updated_line


def main(argv: list[str]) -> int:
    if not argv:
        print(usage(), file=sys.stderr)
        return 2
    if argv[0] in ("-h", "-help"):
        print(usage())
        return 0

    mode = argv[0]
    if mode not in ("select", "record"):
        print(f"ERROR: unknown mode: {mode}", file=sys.stderr)
        print(usage(), file=sys.stderr)
        return 2

    try:
        flags = parse_flags(argv[1:])
    except ValueError as exc:
        if str(exc) == "help":
            print(usage())
            return 0
        print(f"ERROR: {exc}", file=sys.stderr)
        print(usage(), file=sys.stderr)
        return 2

    if mode == "select":
        plans = flags.get("-plans")
        progress = flags.get("-progress")
        if not plans or not progress:
            print("ERROR: -plans and -progress are required", file=sys.stderr)
            print(usage(), file=sys.stderr)
            return 2
        code, message = select_plan(Path(plans), Path(progress))
        if code != 0:
            print(message, file=sys.stderr)
            return code
        print(message)
        return 0

    plan = flags.get("-plan")
    status = flags.get("-status")
    progress = flags.get("-progress")
    note = flags.get("-note")
    if not plan or not status or not progress:
        print("ERROR: -plan, -status, and -progress are required", file=sys.stderr)
        print(usage(), file=sys.stderr)
        return 2
    code, message = record_status(plan, status, Path(progress), note)
    if code != 0:
        print(message, file=sys.stderr)
        return code
    print(message)
    return 0


if __name__ == "__main__":
    raise SystemExit(main(sys.argv[1:]))