import io
import os
import re
import shutil
import zipfile
from pathlib import Path
from typing import List

from fastapi import FastAPI, HTTPException, UploadFile, File
from fastapi.responses import FileResponse, StreamingResponse
from fastapi.staticfiles import StaticFiles
from pydantic import BaseModel

PROJECTS_DIR = Path(os.environ.get("PROJECTS_DIR", "/data/projects")).resolve()
PROJECTS_DIR.mkdir(parents=True, exist_ok=True)

ALLOWED_EXTENSIONS = {".stl", ".3mf"}
NAME_PATTERN = re.compile(r"^[A-Za-z0-9 _\-]+$")

app = FastAPI(title="3D Project Manager")


def safe_project_path(name: str) -> Path:
    """Validate a project name and return its resolved path, guarding
    against path traversal / invalid characters."""
    if not name or not NAME_PATTERN.match(name):
        raise HTTPException(400, "Invalid project name")
    path = (PROJECTS_DIR / name).resolve()
    if path.parent != PROJECTS_DIR:
        raise HTTPException(400, "Invalid project name")
    return path


def safe_filename(filename: str) -> str:
    name = Path(filename).name
    if not name or name in (".", ".."):
        raise HTTPException(400, "Invalid file name")
    return name


class ProjectCreate(BaseModel):
    name: str


@app.get("/api/projects")
def list_projects():
    projects = []
    for entry in sorted(PROJECTS_DIR.iterdir()):
        if entry.is_dir():
            file_count = sum(
                1 for f in entry.iterdir()
                if f.is_file() and f.suffix.lower() in ALLOWED_EXTENSIONS
            )
            projects.append({"name": entry.name, "file_count": file_count})
    return projects


@app.post("/api/projects")
def create_project(payload: ProjectCreate):
    path = safe_project_path(payload.name)
    if path.exists():
        raise HTTPException(409, "A project with this name already exists")
    path.mkdir(parents=True)
    return {"name": payload.name}


@app.delete("/api/projects/{name}")
def delete_project(name: str):
    path = safe_project_path(name)
    if not path.exists():
        raise HTTPException(404, "Project not found")
    shutil.rmtree(path)
    return {"status": "deleted"}


@app.get("/api/projects/{name}/files")
def list_files(name: str):
    path = safe_project_path(name)
    if not path.exists():
        raise HTTPException(404, "Project not found")
    files = []
    for f in sorted(path.iterdir()):
        if f.is_file() and f.suffix.lower() in ALLOWED_EXTENSIONS:
            files.append({
                "name": f.name,
                "size": f.stat().st_size,
                "type": f.suffix.lower().lstrip("."),
            })
    return files


@app.post("/api/projects/{name}/upload")
async def upload_files(name: str, files: List[UploadFile] = File(...)):
    path = safe_project_path(name)
    if not path.exists():
        raise HTTPException(404, "Project not found")

    saved, skipped = [], []
    for upload in files:
        ext = Path(upload.filename).suffix.lower()
        if ext not in ALLOWED_EXTENSIONS:
            skipped.append(upload.filename)
            continue
        filename = safe_filename(upload.filename)
        dest = path / filename
        with open(dest, "wb") as out:
            shutil.copyfileobj(upload.file, out)
        saved.append(filename)

    return {"saved": saved, "skipped": skipped}


@app.get("/api/projects/{name}/files/{filename}")
def get_file(name: str, filename: str):
    path = safe_project_path(name)
    target = path / safe_filename(filename)
    if not target.exists():
        raise HTTPException(404, "File not found")
    return FileResponse(target)


@app.get("/api/download-all")
def download_all_projects():
    projects = [p for p in PROJECTS_DIR.iterdir() if p.is_dir()]
    files_found = False

    buffer = io.BytesIO()
    with zipfile.ZipFile(buffer, "w", zipfile.ZIP_DEFLATED) as zf:
        for project in projects:
            for f in project.iterdir():
                if f.is_file() and f.suffix.lower() in ALLOWED_EXTENSIONS:
                    zf.write(f, arcname=f"{project.name}/{f.name}")
                    files_found = True

    if not files_found:
        raise HTTPException(404, "No files to download")

    buffer.seek(0)
    return StreamingResponse(
        buffer,
        media_type="application/zip",
        headers={"Content-Disposition": 'attachment; filename="alle-projekte.zip"'},
    )


@app.get("/api/projects/{name}/download")
def download_project(name: str):
    path = safe_project_path(name)
    if not path.exists():
        raise HTTPException(404, "Project not found")

    files = [f for f in path.iterdir() if f.is_file() and f.suffix.lower() in ALLOWED_EXTENSIONS]
    if not files:
        raise HTTPException(404, "Project has no files to download")

    buffer = io.BytesIO()
    with zipfile.ZipFile(buffer, "w", zipfile.ZIP_DEFLATED) as zf:
        for f in files:
            zf.write(f, arcname=f.name)
    buffer.seek(0)

    zip_filename = f"{name}.zip"
    return StreamingResponse(
        buffer,
        media_type="application/zip",
        headers={"Content-Disposition": f'attachment; filename="{zip_filename}"'},
    )


@app.delete("/api/projects/{name}/files/{filename}")
def delete_file(name: str, filename: str):
    path = safe_project_path(name)
    target = path / safe_filename(filename)
    if not target.exists():
        raise HTTPException(404, "File not found")
    target.unlink()
    return {"status": "deleted"}


# Serve the frontend last, so it doesn't shadow the /api routes above.
app.mount("/", StaticFiles(directory="/app/static", html=True), name="static")