from datetime import datetime
import sqlite3
import hashlib
import secrets

from flask import Flask, request, abort
from flask.json import jsonify

DB_PATH = "history.db"
PASS_FILE = "pass"
PASS_SALT = b"IgTp9iQH"
CLAIM_TOKEN_FILE = "claim_token"
CORS_ORIGIN = "*"


app = Flask("Schluesselverfolgung")


@app.route("/auth", methods=["POST"])
def auth():
    if "pass" in request.form:
        hashed = hashlib.pbkdf2_hmac("sha512",
                                     request.form["pass"].encode("utf-8"),
                                     PASS_SALT,
                                     10000)
        with open(PASS_FILE, "rb") as f:
            if hashed == f.read():
                new_token = secrets.token_hex(16)
                _add_token(new_token, "claim,query")
                return new_token
            else:
                abort(401)
    else:
        abort(400)


@app.route("/claim", methods=["POST"])
def claim():
    permissions = _check_token()
    if "claim" not in permissions:
        abort(403)

    if "name" not in request.form or "contact" not in request.form:
        abort(400)

    name = request.form["name"].strip()
    contact = request.form["contact"].strip()

    # These are arbitrary values but there to prevent sending an empty form
    if len(name) < 3 or len(contact) < 3:
        abort(400)

    claim_id = _add_claim(name, contact)
    return claim_id


@app.route("/status/<cid>")
def status(cid):
    return _get_claim_status(cid)


@app.route("/keyholder")
def keyholder():
    permissions = _check_token()
    if "query" not in permissions:
        abort(403)

    return jsonify(_get_keyholder())


@app.after_request
def add_header(response):
    if CORS_ORIGIN is not None:
        response.headers['Access-Control-Allow-Origin'] = CORS_ORIGIN
        response.headers['Access-Control-Allow-Headers'] = 'X-Auth-Token'
    return response


def _init_db():
    c = sqlite3.connect(DB_PATH)
    c.execute("""
        CREATE TABLE IF NOT EXISTS History (
            Id INTEGER PRIMARY KEY,
            CId TEXT NOT NULL,
            Name TEXT NOT NULL,
            Contact TEXT NOT NULL,
            Timestamp INTEGER NOT NULL
        )
    """)
    c.execute("""
        CREATE TABLE IF NOT EXISTS Token (
            Id INTEGER PRIMARY KEY,
            Token TEXT NOT NULL UNIQUE,
            Permissions TEXT NOT NULL,
            Timestamp INTEGER NOT NULL
        )
    """)
    with open(CLAIM_TOKEN_FILE) as f:
        c.execute("""
            INSERT OR IGNORE INTO Token (Token, Permissions, Timestamp)
            VALUES (?,?,?)
        """, (f.read(), "claim", datetime.now().timestamp()))
    c.commit()


def _add_token(token, permissions):
    c = sqlite3.connect(DB_PATH)
    conn = c.cursor()
    conn.execute("""
        INSERT INTO Token (Token, Permissions, Timestamp)
        VALUES (?,?,?)
    """, (token, permissions, datetime.now().timestamp()))
    c.commit()


def _check_token():
    if "X-Auth-Token" in request.headers:
        token = request.headers["X-Auth-Token"]
    else:
        abort(401)

    c = sqlite3.connect(DB_PATH)
    conn = c.cursor()
    conn.execute("SELECT Permissions FROM Token WHERE Token=?", (token,))
    row = conn.fetchone()
    if row is None:
        return set()
    else:
        return set(row[0].split(","))


def _add_claim(name, contact):
    claim_id = secrets.token_hex(8)

    c = sqlite3.connect(DB_PATH)
    conn = c.cursor()
    conn.execute("""
        INSERT INTO History (CId, Name, Contact, Timestamp)
        VALUES (?,?,?,?)
    """, (claim_id, name, contact, datetime.now().timestamp()))
    c.commit()

    return claim_id


def _get_claim_status(claim_id):
    c = sqlite3.connect(DB_PATH)
    conn = c.cursor()
    conn.execute("SELECT CId FROM History ORDER BY Timestamp DESC")
    row = conn.fetchone()
    if row is None:
        return "unknown"
    else:
        if row[0] == claim_id:
            return "latest"
        else:
            return "outdated"


def _get_keyholder():
    c = sqlite3.connect(DB_PATH)
    conn = c.cursor()
    conn.execute("""
        SELECT Name, Contact, Timestamp 
        FROM History ORDER BY Timestamp DESC LIMIT 3
    """)
    # Timestamp precision is one minute
    keyholder = [{"name": row[0], "contact": row[1], "timestamp": int(row[2] // 60 * 60)}
                 for row in conn]
    return keyholder


if __name__ == "__main__":
    _init_db()
    app.run()