from __future__ import annotations

from pathlib import Path

from fastapi import APIRouter, Depends, Request
from fastapi.responses import HTMLResponse
from fastapi.templating import Jinja2Templates

from app.api.tasks import get_task_repository
from app.storage import JsonFileTaskRepository, StoredTask


router = APIRouter(tags=["stats"])

templates = Jinja2Templates(directory=str(Path(__file__).resolve().parents[2] / "templates"))


def get_task_status(task: StoredTask) -> str:
    if task.done_at is not None:
        return "done"
    if task.started_at is not None:
        return "in_progress"
    return "backlog"


def format_dt(value: object) -> str:
    if value is None:
        return "—"
    return str(value)


def format_duration(task: StoredTask) -> str:
    if task.started_at is None or task.done_at is None:
        return "—"

    delta = task.done_at - task.started_at
    total_seconds = int(delta.total_seconds())
    hours, remainder = divmod(total_seconds, 3600)
    minutes, seconds = divmod(remainder, 60)
    return f"{hours}h {minutes}m {seconds}s"


def serialize_task(task: StoredTask) -> dict[str, str]:
    return {
        "id": str(task.id),
        "title": task.title,
        "status": get_task_status(task),
        "created_at": task.created_at.isoformat(),
        "started_at": task.started_at.isoformat() if task.started_at is not None else "",
        "done_at": task.done_at.isoformat() if task.done_at is not None else "",
        "cycle_time": format_duration(task),
    }


@router.get("/stats", response_class=HTMLResponse)
def stats_page(
    request: Request,
    repo: JsonFileTaskRepository = Depends(get_task_repository),
) -> HTMLResponse:
    tasks = repo.list_tasks()

    backlog_tasks = [serialize_task(task) for task in tasks if get_task_status(task) == "backlog"]
    in_progress_tasks = [serialize_task(task) for task in tasks if get_task_status(task) == "in_progress"]
    done_tasks = [serialize_task(task) for task in tasks if get_task_status(task) == "done"]

    selected_task = None
    if tasks:
        selected_task = serialize_task(tasks[0])

    return templates.TemplateResponse(
        request=request,
        name="stats.html",
        context={
            "selected_task": selected_task,
            "backlog_tasks": backlog_tasks,
            "in_progress_tasks": in_progress_tasks,
            "done_tasks": done_tasks,
        },
    )