import csv
import struct

from django.db.models import Count
from django.http import HttpRequest, HttpResponse
from ninja import Router
from ninja.decorators import decorate_view
from ninja.security import django_auth_is_staff

from games.decorators import require_game_enabled

from .canvas import read_canvas
from .gif import build_evolution_gif
from .heatmap import (
    build_heatmap_decay_gif,
    build_heatmap_evolution_gif,
    build_heatmap_png,
)
from .models import PixelPlacement, PlaceSettings

router = Router()

PREFIX = "/events/{event_path}/place"

# 4-byte little-endian header (uint16 width, uint16 height) prefixed to the
# canvas payload - the grid can be resized by an admin, so the frontend
# can't hardcode dimensions and needs to read them off the payload itself.
HEADER_FORMAT = "<HH"


@router.get(f"{PREFIX}/canvas")
@decorate_view(require_game_enabled(path="place"))
def canvas(request: HttpRequest, event_path: str):
    """The one-time full-grid load. Every placement after that arrives as a
    single websocket message, never a re-fetch."""
    place_settings = PlaceSettings.current(request.event)
    header = struct.pack(HEADER_FORMAT, place_settings.width, place_settings.height)
    pixels = read_canvas(event_path, place_settings.width, place_settings.height)
    return HttpResponse(header + pixels, content_type="application/octet-stream")


@router.get(f"{PREFIX}/evolution.gif", auth=django_auth_is_staff)
@decorate_view(require_game_enabled(path="place"))
def evolution_gif(request: HttpRequest, event_path: str, players: str = ""):
    """Admin-only: replays the full placement history as an animated GIF.

    `players` is an optional comma-separated list of usernames to only
    replay those players' placements (combined)."""
    usernames = [name.strip() for name in players.split(",") if name.strip()]
    return HttpResponse(
        build_evolution_gif(request.event, usernames), content_type="image/gif"
    )


@router.get(f"{PREFIX}/heatmap.png", auth=django_auth_is_staff)
@decorate_view(require_game_enabled(path="place"))
def heatmap_png(request: HttpRequest, event_path: str, players: str = ""):
    """Admin-only: how many times each pixel was placed, as a heatmap PNG.

    `players` is an optional comma-separated list of usernames to only
    count those players' placements (combined)."""
    usernames = [name.strip() for name in players.split(",") if name.strip()]
    return HttpResponse(
        build_heatmap_png(request.event, usernames), content_type="image/png"
    )


@router.get(f"{PREFIX}/heatmap-evolution.gif", auth=django_auth_is_staff)
@decorate_view(require_game_enabled(path="place"))
def heatmap_evolution_gif(request: HttpRequest, event_path: str, players: str = ""):
    """Admin-only: the heatmap building up over time, as an animated GIF.

    `players` is an optional comma-separated list of usernames to only
    count those players' placements (combined)."""
    usernames = [name.strip() for name in players.split(",") if name.strip()]
    return HttpResponse(
        build_heatmap_evolution_gif(request.event, usernames),
        content_type="image/gif",
    )


@router.get(f"{PREFIX}/heatmap-decay.gif", auth=django_auth_is_staff)
@decorate_view(require_game_enabled(path="place"))
def heatmap_decay_gif(
    request: HttpRequest,
    event_path: str,
    players: str = "",
    half_life: int | None = None,
):
    """Admin-only: the heatmap over time, but heat decays so pixels nobody
    touches anymore fade back to white.

    `players` is an optional comma-separated list of usernames to only
    count those players' placements (combined). `half_life` is in
    placements, defaults to 10 frames' worth."""
    usernames = [name.strip() for name in players.split(",") if name.strip()]
    return HttpResponse(
        build_heatmap_decay_gif(request.event, usernames, half_life),
        content_type="image/gif",
    )


@router.get(f"{PREFIX}/placements.csv", auth=django_auth_is_staff)
@decorate_view(require_game_enabled(path="place"))
def placements_csv(request: HttpRequest, event_path: str):
    """Admin-only: pixel placement count per player, most active first."""
    rows = (
        PixelPlacement.objects.filter(event=request.event)
        .values("player__username")
        .annotate(count=Count("id"))
        .order_by("-count", "player__username")
    )
    # text/plain so browsers render it inline - most force-download text/csv
    response = HttpResponse(content_type="text/plain; charset=utf-8")
    writer = csv.writer(response)
    writer.writerow(["username", "placements"])
    for row in rows:
        writer.writerow(
            [
                row["player__username"],
                row["count"],
            ]
        )
    return response