"""Teacher-only content administration for classroom plans and Demo projects."""
from __future__ import annotations

import json
import re
import shutil
from pathlib import Path, PurePosixPath

from fastapi import APIRouter, HTTPException
from fastapi.responses import FileResponse
from pydantic import BaseModel

import classroom_service as classroom

ROOT = Path(__file__).resolve().parent
PROJECTS = ROOT / "projects"
STATIC = ROOT / "classroom_static"
TEXT_EXTENSIONS = {
    ".py", ".html", ".css", ".js", ".json", ".txt", ".csv", ".md",
    ".toml", ".yaml", ".yml",
}
router = APIRouter()


class AdminAuth(BaseModel):
    password: str


class WeekRequest(AdminAuth):
    week_id: str


class WeekSave(WeekRequest):
    title: str
    project: str
    output: str
    files: dict[str, str]


class ProjectRef(BaseModel):
    class_name: str
    student_name: str
    project_name: str


class DemoRequest(AdminAuth):
    project: ProjectRef


class DemoSave(AdminAuth):
    original: ProjectRef | None = None
    class_name: str
    student_name: str
    project_name: str
    files: dict[str, str]


class ClassroomSubmissionRequest(AdminAuth):
    class_code: str
    student_id: str
    week_id: str


class ClassroomBackupRequest(AdminAuth):
    class_code: str
    week_id: str


def segment(value: str, label: str) -> str:
    text = re.sub(r"[\x00-\x1f\x7f]", "", str(value).strip())[:100]
    if not text or text in {".", ".."} or "/" in text or "\\" in text:
        raise HTTPException(400, f"{label}不合法")
    return text


def text_path(value: str) -> str:
    raw = str(value).replace("\\", "/").strip("/")
    path = PurePosixPath(raw)
    if (
        not raw or path.is_absolute() or ".." in path.parts or len(raw) > 180
        or path.suffix.lower() not in TEXT_EXTENSIONS
    ):
        raise HTTPException(400, f"檔案路徑不合法：{value}")
    return path.as_posix()


def project_root(ref: ProjectRef) -> Path:
    return PROJECTS / segment(ref.class_name, "班級名稱") / segment(ref.student_name, "學生名稱") / segment(ref.project_name, "專題名稱")


def relative_repo_path(path: Path) -> str:
    return path.relative_to(ROOT).as_posix()


def commit_changes(additions: dict[str, bytes | Path], deletions: list[str], message: str):
    if not classroom.TOKEN:
        raise HTTPException(503, "請先在 Space Secrets 設定 HF_TOKEN")
    from huggingface_hub import CommitOperationAdd, CommitOperationDelete, HfApi

    add_paths = set(additions)
    operations = [
        CommitOperationDelete(path_in_repo=path)
        for path in sorted(set(deletions) - add_paths)
    ]
    operations.extend(
        CommitOperationAdd(path_in_repo=path, path_or_fileobj=value)
        for path, value in sorted(additions.items())
    )
    if not operations:
        return None
    return HfApi(token=classroom.TOKEN).create_commit(
        repo_id=classroom.REPO,
        repo_type="space",
        operations=operations,
        commit_message=message,
    )


def load_course() -> dict:
    return json.loads((classroom.DATA / "course.json").read_text(encoding="utf-8"))


def scan_demo() -> list[dict]:
    projects = []
    if not PROJECTS.is_dir():
        return projects
    for class_dir in sorted(path for path in PROJECTS.iterdir() if path.is_dir() and not path.name.startswith(".")):
        for student_dir in sorted(path for path in class_dir.iterdir() if path.is_dir() and not path.name.startswith(".")):
            for item in sorted(path for path in student_dir.iterdir() if path.is_dir() and not path.name.startswith(".")):
                kind = "python" if (item / "main.py").is_file() else "html" if (item / "index.html").is_file() else "external" if (item / "link.txt").is_file() else "asset"
                projects.append({
                    "class_name": class_dir.name,
                    "student_name": student_dir.name,
                    "project_name": item.name,
                    "type": kind,
                })
    return projects


def read_editable_text(path: Path) -> str | None:
    if path.suffix.lower() not in TEXT_EXTENSIONS or path.stat().st_size > 800_000:
        return None
    try:
        return path.read_text(encoding="utf-8")
    except UnicodeDecodeError:
        return None


def editable_project(root: Path) -> dict:
    if not root.is_dir():
        raise HTTPException(404, "找不到這個 Demo 專題")
    files: dict[str, str] = {}
    assets: list[str] = []
    for path in sorted(item for item in root.rglob("*") if item.is_file()):
        rel = path.relative_to(root).as_posix()
        content = read_editable_text(path)
        if content is None:
            assets.append(rel)
        else:
            files[rel] = content
    return {"files": files, "assets": assets}


@router.get("/admin")
def admin_page():
    return FileResponse(STATIC / "admin.html")


@router.post("/api/admin/state")
def admin_state(req: AdminAuth):
    classroom.check_password(req.password)
    return {"course": load_course(), "demo_projects": scan_demo(), "classrooms": {"courses": classroom.catalog()["courses"], "submissions": classroom.submission_catalog()}}


@router.post("/api/admin/classroom/submission")
def admin_submission(req: ClassroomSubmissionRequest):
    classroom.check_password(req.password)
    state = classroom.get_submission(req.class_code, req.student_id, req.week_id)
    return {"submission": classroom.submission_payload(state)}


@router.post("/api/admin/classroom/backup")
def backup_submissions(req: ClassroomBackupRequest):
    classroom.check_password(req.password)
    class_code = classroom.clean(req.class_code, "")
    week_id = classroom.clean(req.week_id, "")
    states = classroom.finals(class_code, week_id)
    if not states:
        raise HTTPException(400, "這個 Lesson 還沒有學生提交")
    additions = {}
    for state in states:
        path = classroom.submission_path(class_code, state["student_id"], week_id)
        content = (json.dumps(classroom.submission_payload(state), ensure_ascii=False, indent=2) + "\n").encode()
        additions[relative_repo_path(path)] = content
    result = commit_changes(additions, [], f"Backup {class_code} {week_id} classroom submissions")
    for repo_path, content in additions.items():
        path = ROOT / repo_path
        path.parent.mkdir(parents=True, exist_ok=True)
        path.write_bytes(content)
    return {"ok": True, "count": len(states), "commit_url": str(result.commit_url) if result else ""}


@router.post("/api/admin/classroom/submission/delete")
def delete_submission(req: ClassroomSubmissionRequest):
    classroom.check_password(req.password)
    state = classroom.get_submission(req.class_code, req.student_id, req.week_id)
    path = classroom.submission_path(state["class_code"], state["student_id"], state["week_id"])
    result = commit_changes({}, [relative_repo_path(path)] if path.is_file() else [], f"Delete {state['class_code']} {state['week_id']} submission for {state['display_name']}")
    with classroom.lock, classroom.sqlite3.connect(classroom.DB) as db:
        db.execute("UPDATE classroom_projects SET final_files=NULL,submitted_at=NULL WHERE class_code=? AND student_id=? AND week_id=?",(state["class_code"],state["student_id"],state["week_id"]))
    path.unlink(missing_ok=True)
    return {"ok": True, "commit_url": str(result.commit_url) if result else ""}


@router.post("/api/admin/week")
def admin_week(req: WeekRequest):
    classroom.check_password(req.password)
    week_id = classroom.clean(req.week_id, "")
    course = load_course()
    week = next((item for item in course.get("weeks", []) if item.get("id") == week_id), None)
    if not week:
        raise HTTPException(404, "找不到這個 Lesson")
    root = classroom.TEMPLATES / week_id
    files = {}
    if root.is_dir():
        for path in sorted(item for item in root.rglob("*") if item.is_file()):
            rel = path.relative_to(root).as_posix()
            if path.suffix.lower() in TEXT_EXTENSIONS:
                files[rel] = path.read_text(encoding="utf-8")
    return {"week": week, "files": files}


@router.post("/api/admin/week/save")
def save_week(req: WeekSave):
    classroom.check_password(req.password)
    week_id = classroom.clean(req.week_id, "")
    files = {text_path(path): str(content) for path, content in req.files.items()}
    course = load_course()
    week = next((item for item in course.get("weeks", []) if item.get("id") == week_id), None)
    if not week:
        raise HTTPException(404, "找不到這個 Lesson")
    week.update({
        "title": classroom.clean_label(req.title, week.get("title", "")),
        "project": classroom.clean_label(req.project, week.get("project", "")),
        "output": classroom.clean_label(req.output, week.get("output", ""), 160),
        "template": bool(files),
    })
    course_bytes = (json.dumps(course, ensure_ascii=False, indent=2) + "\n").encode()
    root = classroom.TEMPLATES / week_id
    old = [path for path in root.rglob("*") if path.is_file()] if root.is_dir() else []
    additions = {"classroom_data/course.json": course_bytes}
    additions.update({f"classroom_data/templates/{week_id}/{path}": content.encode() for path, content in files.items()})
    deletions = [relative_repo_path(path) for path in old if path.relative_to(root).as_posix() not in files]
    result = commit_changes(additions, deletions, f"Update classroom {week_id}")

    (classroom.DATA / "course.json").write_bytes(course_bytes)
    root.mkdir(parents=True, exist_ok=True)
    for path in old:
        if path.relative_to(root).as_posix() not in files:
            path.unlink(missing_ok=True)
    for rel, content in files.items():
        target = root / rel
        target.parent.mkdir(parents=True, exist_ok=True)
        target.write_text(content, encoding="utf-8")
    return {"ok": True, "commit_url": str(result.commit_url) if result else ""}


@router.post("/api/admin/demo/project")
def admin_demo_project(req: DemoRequest):
    classroom.check_password(req.password)
    return editable_project(project_root(req.project))


@router.post("/api/admin/demo/save")
def save_demo(req: DemoSave):
    classroom.check_password(req.password)
    target_ref = ProjectRef(
        class_name=segment(req.class_name, "班級名稱"),
        student_name=segment(req.student_name, "學生名稱"),
        project_name=segment(req.project_name, "專題名稱"),
    )
    target = project_root(target_ref)
    original = project_root(req.original) if req.original else None
    if original and not original.is_dir():
        raise HTTPException(404, "原始 Demo 專題不存在")
    if target != original and target.exists():
        raise HTTPException(409, "目標位置已有同名專題")
    files = {text_path(path): str(content) for path, content in req.files.items()}
    if not any(name in files for name in ("main.py", "index.html", "link.txt")):
        raise HTTPException(400, "專題至少需要 main.py、index.html 或 link.txt 其中一個入口")

    existing = [path for path in original.rglob("*") if path.is_file()] if original else []
    additions: dict[str, bytes | Path] = {}
    target_prefix = relative_repo_path(target)
    if target != original:
        for path in existing:
            rel = path.relative_to(original).as_posix()
            if read_editable_text(path) is None:
                additions[f"{target_prefix}/{rel}"] = path
    additions.update({f"{target_prefix}/{rel}": content.encode() for rel, content in files.items()})
    if target == original:
        deletions = [relative_repo_path(path) for path in existing if read_editable_text(path) is not None and path.relative_to(original).as_posix() not in files]
    else:
        deletions = [relative_repo_path(path) for path in existing]
    result = commit_changes(additions, deletions, f"Update Demo project {target_ref.project_name}")

    if original and target != original:
        target.parent.mkdir(parents=True, exist_ok=True)
        shutil.copytree(original, target)
        shutil.rmtree(original)
    else:
        target.mkdir(parents=True, exist_ok=True)
    for path in list(target.rglob("*")):
        if path.is_file() and read_editable_text(path) is not None and path.relative_to(target).as_posix() not in files:
            path.unlink()
    for rel, content in files.items():
        path = target / rel
        path.parent.mkdir(parents=True, exist_ok=True)
        path.write_text(content, encoding="utf-8")
    project_data = target_ref.model_dump() if hasattr(target_ref, "model_dump") else target_ref.dict()
    return {"ok": True, "project": project_data, "commit_url": str(result.commit_url) if result else ""}


@router.post("/api/admin/demo/delete")
def delete_demo(req: DemoRequest):
    classroom.check_password(req.password)
    root = project_root(req.project)
    if not root.is_dir():
        raise HTTPException(404, "找不到這個 Demo 專題")
    paths = [path for path in root.rglob("*") if path.is_file()]
    result = commit_changes({}, [relative_repo_path(path) for path in paths], f"Delete Demo project {root.name}")
    shutil.rmtree(root)
    return {"ok": True, "commit_url": str(result.commit_url) if result else ""}