import asyncio
import json
import shutil
import uuid
from datetime import datetime, timezone

from fastapi import APIRouter, HTTPException
from fastapi.responses import FileResponse

from agents import provider_available
from config import PROJECTS_DIR, PROVIDERS
from database import (
    create_guide, delete_guide, get_guide, list_guides,
    create_topic, list_topics as db_list_topics, delete_topic,
    list_progress, set_progress, delete_progress,
)
from generator import (
    generate_guide, cancel_guide, chat_with_guide, guide_slot_dateien,
    generate_bausteine, cancel_bausteine, bausteine_status, active_bausteine, reset_bausteine,
)
from models import (
    GuideCreateRequest, GuideResponse,
    TopicCreateRequest,
    BausteineCreateRequest, BausteineStatusResponse,
    GuideChatRequest, GuideChatResponse,
    ProgressUpdate, ProgressResponse, ProjectResponse, ProviderInfo,
)
from paths import bausteine_path, bausteine_topics, guide_content_path, project_dir, topic_dir

router = APIRouter(prefix="/api")


@router.get("/providers", response_model=list[ProviderInfo])
async def get_providers():
    return [{"id": pid, "available": provider_available(pid)} for pid in PROVIDERS]


@router.get("/topics")
async def get_topics():
    db_topics = await db_list_topics()
    guides = await list_guides()
    derived = {g["topic"] for g in guides}
    derived.update(bausteine_topics())
    derived.update(job["topic"] for job in active_bausteine())
    # DB ist führend (Reihenfolge: neueste zuerst); Abgeleitetes ohne DB-Eintrag hinten anhängen
    return db_topics + sorted(derived - set(db_topics))


# Lernschulden-Regel: JE Format (MiniGuide/Guide/FullGuide) höchstens 5 erstellte,
# aber nicht absolvierte Guides. Darüber sind nur Neu-Generierungen bereits
# erstellter Guides erlaubt. Themen, Bausteine und OnePager sind unbegrenzt.
MAX_OFFENE_GUIDES = 5


async def _formate_stats() -> dict:
    """Pro Format erstellt/absolviert (alle Kapitel abgehakt) — pro Thema zählt nur der neueste fertige Guide."""
    guides = await list_guides()
    formate = {}
    for fmt in ("MiniGuide", "Guide", "FullGuide"):
        neueste: dict[str, dict] = {}
        for g in guides:
            if g["format"] == fmt and g["status"] == "done":
                if g["topic"] not in neueste or g["created_at"] > neueste[g["topic"]]["created_at"]:
                    neueste[g["topic"]] = g
        absolviert = 0
        for g in neueste.values():
            path = guide_content_path(g["topic"], fmt)
            if not path.exists():
                continue
            try:
                chapters = json.loads(path.read_text(encoding="utf-8")).get("chapters", [])
            except ValueError:
                continue
            titles = {c.get("title") for c in chapters}
            if titles and titles <= set(await list_progress(g["id"])):
                absolviert += 1
        formate[fmt] = {"erstellt": len(neueste), "absolviert": absolviert}
    return formate


@router.get("/stats")
async def get_stats():
    """Tracker: Themen-Anzahl + pro Format erstellt/absolviert."""
    guides = await list_guides()
    themen = set(await db_list_topics()) | {g["topic"] for g in guides} | set(bausteine_topics())
    if PROJECTS_DIR.is_dir():
        themen |= {e.name for e in PROJECTS_DIR.iterdir() if e.is_dir()}
    return {"themen": len(themen), "formate": await _formate_stats()}


@router.post("/topics")
async def add_topic(req: TopicCreateRequest):
    await create_topic(req.name.strip())
    return {"ok": True}


@router.delete("/topics")
async def remove_topic(topic: str):
    await delete_topic(topic)
    shutil.rmtree(topic_dir(topic), ignore_errors=True)
    return {"ok": True}


def _safe_project_name(name: str) -> str:
    if not name or "/" in name or "\\" in name or ".." in name or "\x00" in name:
        raise HTTPException(400, "Ungültiger Projektname")
    return name


@router.get("/projects", response_model=list[ProjectResponse])
async def list_projects():
    if not PROJECTS_DIR.is_dir():
        return []
    return [{"name": entry.name} for entry in sorted(PROJECTS_DIR.iterdir()) if entry.is_dir()]


@router.delete("/projects/{name}")
async def remove_project(name: str):
    _safe_project_name(name)
    pdir = project_dir(name)
    if not pdir.is_dir():
        raise HTTPException(404, "Projekt nicht gefunden")
    shutil.rmtree(pdir)
    return {"ok": True}


# --- Bausteine ---

@router.get("/bausteine/status", response_model=BausteineStatusResponse)
async def get_bausteine_status(topic: str):
    return bausteine_status(topic)


@router.get("/bausteine/active")
async def get_active_bausteine():
    return active_bausteine()


@router.post("/bausteine")
async def create_bausteine(req: BausteineCreateRequest):
    topic = req.topic.strip()
    if bausteine_status(topic)["generating"]:
        return {"ok": True, "status": "already_generating"}
    await create_topic(topic)
    asyncio.create_task(generate_bausteine(topic, req.instructions.strip(), req.provider))
    return {"ok": True}


@router.post("/bausteine/cancel")
async def cancel_bausteine_route(topic: str):
    if not cancel_bausteine(topic):
        raise HTTPException(404, "Keine laufende Generierung")
    return {"ok": True}


@router.delete("/bausteine")
async def remove_bausteine(topic: str):
    reset_bausteine(topic)
    return {"ok": True}


# --- Guides ---

@router.post("/guides", response_model=GuideResponse)
async def create(req: GuideCreateRequest):
    if req.format != "OnePager" and not bausteine_path(req.topic.strip()).exists():
        raise HTTPException(400, "Erst Bausteine erstellen")
    # Kein Duplikat-Start: pro Thema+Format höchstens eine laufende Generierung
    for g in await list_guides():
        if g["topic"] == req.topic.strip() and g["format"] == req.format and g["status"] in ("queued", "generating"):
            raise HTTPException(409, "Generierung läuft bereits")
    # Lernschulden-Regel: neue Guides nur, wenn das Format weniger als 5 offene hat (erstellt, nicht absolviert).
    # Resume (Schritt-Dateien vorhanden) ist ausgenommen — der Guide wurde bereits angefangen.
    content = guide_content_path(req.topic.strip(), req.format)
    if req.format != "OnePager" and not content.exists() and not guide_slot_dateien(content):
        stat = (await _formate_stats()).get(req.format, {"erstellt": 0, "absolviert": 0})
        offen = stat["erstellt"] - stat["absolviert"]
        if offen >= MAX_OFFENE_GUIDES:
            raise HTTPException(409, f"Erst {req.format}s absolvieren — maximal {MAX_OFFENE_GUIDES} offene erlaubt ({offen} offen)")
    await create_topic(req.topic.strip())
    now = datetime.now(timezone.utc).isoformat()
    guide = {
        "id": str(uuid.uuid4()),
        "topic": req.topic.strip(),
        "format": req.format,
        "instructions": req.instructions.strip(),
        "status": "queued",
        "progress": None,
        "created_at": now,
        "updated_at": now,
    }
    await create_guide(guide)
    asyncio.create_task(generate_guide(guide["id"], guide["topic"], guide["format"], guide["instructions"], req.provider))
    return guide


@router.get("/guides", response_model=list[GuideResponse])
async def list_all():
    return await list_guides()


@router.get("/guides/{guide_id}", response_model=GuideResponse)
async def get_one(guide_id: str):
    guide = await get_guide(guide_id)
    if guide is None:
        raise HTTPException(404, "Guide nicht gefunden")
    return guide


@router.get("/guides/{guide_id}/content")
async def guide_content(guide_id: str):
    guide = await get_guide(guide_id)
    if guide is None:
        raise HTTPException(404, "Guide nicht gefunden")
    if guide["status"] != "done":
        raise HTTPException(404, "Inhalt nicht verfügbar")
    path = guide_content_path(guide["topic"], guide["format"])
    if not path.exists():
        raise HTTPException(404, "Datei nicht gefunden")
    return FileResponse(path, media_type="application/json")


@router.post("/guides/{guide_id}/chat", response_model=GuideChatResponse)
async def guide_chat(guide_id: str, req: GuideChatRequest):
    guide = await get_guide(guide_id)
    if guide is None:
        raise HTTPException(404, "Guide nicht gefunden")
    reply = await chat_with_guide(
        guide["topic"], guide["format"], req.section, req.outline,
        [m.model_dump() for m in req.messages],
        provider=req.provider,
    )
    return {"reply": reply}


@router.post("/guides/{guide_id}/cancel")
async def cancel(guide_id: str):
    cancelled = await cancel_guide(guide_id)
    if not cancelled:
        raise HTTPException(404, "Kein aktiver Prozess gefunden")
    return {"ok": True}


@router.delete("/guides/{guide_id}")
async def remove(guide_id: str, slots: bool = False):
    guide = await get_guide(guide_id)
    if guide is None:
        raise HTTPException(404, "Guide nicht gefunden")
    await delete_progress(guide_id)
    await delete_guide(guide_id)
    # Content-/Schritt-Dateien teilen sich alle Läufe eines Thema+Formats — erst löschen,
    # wenn kein Eintrag sie mehr braucht. Teilfortschritt (Schritt-Dateien ohne fertigen
    # Content) bleibt fürs Resume erhalten, außer es wird explizit verlangt (slots=1).
    rest = [g for g in await list_guides() if g["topic"] == guide["topic"] and g["format"] == guide["format"]]
    if not rest:
        content = guide_content_path(guide["topic"], guide["format"])
        if slots or content.exists():
            for p in guide_slot_dateien(content):
                p.unlink(missing_ok=True)
            content.unlink(missing_ok=True)
    return {"ok": True}


@router.get("/guides/{guide_id}/progress", response_model=ProgressResponse)
async def get_progress(guide_id: str):
    guide = await get_guide(guide_id)
    if guide is None:
        raise HTTPException(404, "Guide nicht gefunden")
    return {"chapters": await list_progress(guide_id)}


@router.post("/guides/{guide_id}/progress", response_model=ProgressResponse)
async def update_progress(guide_id: str, req: ProgressUpdate):
    guide = await get_guide(guide_id)
    if guide is None:
        raise HTTPException(404, "Guide nicht gefunden")
    await set_progress(guide_id, req.chapter, req.done)
    return {"chapters": await list_progress(guide_id)}