import json
from datetime import timedelta

import flask as flask
from common import dateutil, database
from dateutil.parser import ParserError
from flask import request, jsonify, Response, render_template

app = flask.Flask('buscribe')


@app.template_filter()
def convert_vtt_timedelta(delta: timedelta):
    return f'{delta.days * 24 + delta.seconds // 3600:02}:{(delta.seconds % 3600) // 60:02}:{delta.seconds % 60:02}.{delta.microseconds // 1000:03}'

def round_bus_time(delta: timedelta):
    """Round bus time down to the second."""
    return f'{delta.days * 24 + delta.seconds // 3600:02}:{(delta.seconds % 3600) // 60:02}:{delta.seconds % 60:02}'

@app.route('/buscribe/vtt')
def get_vtt():
    """Returns WebVTT subtitle file for the period between start_time and end_time.

    Times are relative to --bustime-start.

    TODO: Figure out proper offsets."""
    try:
        start_time_string = request.args.get('start_time')
        start_time = dateutil.parse(start_time_string)
    except ParserError:
        return "Invalid start time!", 400
    except KeyError:
        return "Missing start time!", 400

    try:
        end_time_string = request.args['end_time']
        end_time = dateutil.parse(end_time_string)
    except ParserError:
        return "Invalid end time!", 400
    except KeyError:
        return "Missing end time!", 400

    db_conn = app.db_manager.get_conn()

    results = fetch_lines(db_conn, start_time, end_time)

    return Response(
        render_template("busubs.jinja", results=results, bustime_start=app.bustime_start,
                        duration_extend=timedelta(seconds=0.3)),
        mimetype="text/vtt"
    )


@app.route('/buscribe/json')
def get_json():
    """Searches the line database for *query*, with optional start_time and end_time boundaries.

    Search is done using PostgreSQL websearch_to_tsquery()
    (https://www.postgresql.org/docs/13/functions-textsearch.html)"""

    start_time_string = request.args.get('start_time')
    if start_time_string is not None:
        try:
            start_time = dateutil.parse(start_time_string)
        except ParserError:
            return "Invalid start time!", 400
    else:
        start_time = None

    end_time_string = request.args.get('end_time')
    if end_time_string is not None:
        try:
            end_time = dateutil.parse(end_time_string)
        except ParserError:
            return "Invalid end time!", 400
    else:
        end_time = None

    # I think websearch_to_tsquery() sanitizes its own input.
    query = request.args.get('query', default=None)

    db_conn = app.db_manager.get_conn()

    results = fetch_lines(db_conn, start_time, end_time, query)

    return jsonify([{"start_time": row.start_time.isoformat(),
                     "start_bus_time": round_bus_time(row.start_time - app.bustime_start),
                     "end_time": row.end_time.isoformat(),
                     "end_bus_time": round_bus_time(row.start_time - app.bustime_start),
                     "text": row.transcription_line} for row in results])


def fetch_lines(db_conn, start_time, end_time, query=None):
    if query is None:
        return database.query(db_conn, "SELECT * FROM buscribe_transcriptions WHERE "
                                       "start_time > %s AND "
                                       "end_time < %s;",
                              start_time if start_time is not None else '-infinity',
                              end_time if end_time is not None else 'infinity')
    else:
        return database.query(db_conn, "SELECT * FROM buscribe_transcriptions WHERE "
                                       "start_time > %s AND "
                                       "end_time < %s AND "
                                       "to_tsvector(transcription_line) @@ websearch_to_tsquery(%s);",
                              start_time if start_time is not None else '-infinity',
                              end_time if end_time is not None else 'infinity',
                              query)