"""Local notes starter. Run python3 server.py and visit http://127.0.0.1:8765."""
import json
import sqlite3
from http.server import BaseHTTPRequestHandler, HTTPServer
from pathlib import Path


class Notes:
    def __init__(self, path):
        self.path = path
        with sqlite3.connect(path) as db:
            db.execute("CREATE TABLE IF NOT EXISTS notes(id INTEGER PRIMARY KEY, body TEXT NOT NULL)")

    def list(self):
        with sqlite3.connect(self.path) as db:
            return [{"id": row[0], "body": row[1]} for row in db.execute("SELECT id,body FROM notes ORDER BY id DESC")]

    def add(self, body):
        if not isinstance(body, str) or not body.strip() or len(body) > 2000:
            raise ValueError("A note must contain 1–2000 characters")
        with sqlite3.connect(self.path) as db:
            cursor = db.execute("INSERT INTO notes(body) VALUES (?)", (body.strip(),))
            return {"id": cursor.lastrowid, "body": body.strip()}

    def delete(self, note_id):
        with sqlite3.connect(self.path) as db:
            return db.execute("DELETE FROM notes WHERE id=?", (note_id,)).rowcount > 0


class Handler(BaseHTTPRequestHandler):
    def send(self, status, payload, content_type="application/json"):
        data = payload.encode() if isinstance(payload, str) else json.dumps(payload).encode()
        self.send_response(status)
        self.send_header("Content-Type", content_type)
        self.send_header("Content-Length", str(len(data)))
        self.send_header("X-Content-Type-Options", "nosniff")
        self.send_header("Cache-Control", "no-store")
        self.end_headers()
        self.wfile.write(data)

    def valid_host(self):
        return self.headers.get("Host") == "127.0.0.1:8765"

    def do_GET(self):
        if not self.valid_host():
            return self.send(403, {"error": "Use http://127.0.0.1:8765"})
        if self.path == "/":
            return self.send(200, Path(__file__).with_name("index.html").read_text(), "text/html; charset=utf-8")
        if self.path == "/notes":
            return self.send(200, self.server.notes.list())
        self.send(404, {"error": "Not found"})

    def do_POST(self):
        if not self.valid_host() or self.headers.get("Origin") not in (None, "http://127.0.0.1:8765"):
            return self.send(403, {"error": "Origin not allowed"})
        if self.path != "/notes":
            return self.send(404, {"error": "Not found"})
        if self.headers.get("Content-Type") != "application/json":
            return self.send(415, {"error": "Use application/json"})
        try:
            size = int(self.headers.get("Content-Length", "0"))
            if not 0 < size <= 10000:
                raise ValueError("Invalid request size")
            value = json.loads(self.rfile.read(size))
            if not isinstance(value, dict):
                raise ValueError("Expected an object")
            self.send(201, self.server.notes.add(value.get("body")))
        except (ValueError, UnicodeDecodeError) as error:
            self.send(400, {"error": str(error)})

    def do_DELETE(self):
        if not self.valid_host() or self.headers.get("Origin") not in (None, "http://127.0.0.1:8765"):
            return self.send(403, {"error": "Origin not allowed"})
        try:
            if not self.path.startswith("/notes/"):
                raise ValueError()
            found = self.server.notes.delete(int(self.path.removeprefix("/notes/")))
            self.send(200 if found else 404, {"deleted": found})
        except ValueError:
            self.send(404, {"error": "Not found"})


if __name__ == "__main__":
    server = HTTPServer(("127.0.0.1", 8765), Handler)
    server.notes = Notes(str(Path(__file__).with_name("notes.sqlite3")))
    print("Open http://127.0.0.1:8765 — Ctrl+C to stop")
    try:
        server.serve_forever()
    except KeyboardInterrupt:
        server.server_close()