"""Memoir service — 回忆录编排（章节生成、状态流转）；通过 MemoryService 获取 evidence。"""

import asyncio
from typing import List, Optional

from fastapi import HTTPException
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import joinedload

from app.agents.memoir.prompts import (
    CHAPTER_CATEGORIES,
    CHAPTER_ORDER,
    STAGE_TO_ORDER,
)
from app.core.logging import get_logger
from app.core.storage_purge import delete_object_storage_keys_best_effort
from app.features.memoir import repo
from app.features.memoir.asset_resolver import (
    collect_asset_ids_for_chapter,
    collect_asset_ids_for_chapters,
    strip_legacy_image_placeholders,
)
from app.features.memoir.asset_urls import signed_urls_for_asset_ids
from app.features.memoir.chapter_markdown_compose import (
    materialize_chapter_markdown_from_loaded_chapter,
)
from app.features.memoir.cover_eligibility import primary_chapter_memoir_image
from app.features.memoir.helpers import (
    chapter_to_dict,
    chapter_to_list_dict,
    is_image_permanently_unavailable,
)
from app.features.memoir.memoir_images.settings import MemoirImageSettings
from app.features.memoir.models import Book, Chapter, ChapterStoryLink
from app.features.memory.service import MemoryService
from app.ports.storage import ObjectStorage

logger = get_logger(__name__)


async def get_or_create_book(user_id: str, db: AsyncSession):
    """Get the user's current book or return None."""
    return await repo.get_current_book(user_id, db)


class MemoirService:
    def __init__(
        self,
        db: AsyncSession,
        memory_service: Optional[MemoryService] = None,
        *,
        object_storage: ObjectStorage | None = None,
    ):
        self._db = db
        self._memory = memory_service
        self._object_storage = object_storage

    async def get_evidence(self, user_id: str, query: str, *, top_k: int = 10) -> dict:
        """通过 MemoryService 获取检索证据（章节生成时优先使用）。"""
        if self._memory is None:
            return {
                "relevant_chunks": [],
                "relevant_summaries": [],
                "relevant_facts": [],
                "timeline_hints": [],
            }
        return await self._memory.retrieve(user_id, query, top_k=top_k)

    async def _cleanup_unavailable_images(self, ch: Chapter) -> None:
        cleaned = False
        for rec in getattr(ch, "images", None) or []:
            if rec and is_image_permanently_unavailable(rec):
                logger.info("清理不可用配图: chapter=%s, image=%s", ch.id, rec.id)
                await self._db.delete(rec)
                cleaned = True
        if cleaned:
            await self._db.commit()
            await self._db.refresh(ch)

    async def get_current_book(self, user_id: str) -> dict:
        book = await repo.get_current_book(user_id, self._db)
        if not book:
            return {"message": "No book found"}
        return {
            "id": book.id,
            "title": book.title,
            "total_pages": book.total_pages,
            "total_words": book.total_words,
            "cover_image_url": book.cover_image_url,
            "has_update": book.has_update,
            "last_update_chapter_id": book.last_update_chapter_id,
        }

    async def clear_book_update(self, user_id: str) -> dict:
        book = await repo.get_current_book(user_id, self._db)
        if not book:
            return {"status": "ok", "message": "No book found"}
        book.has_update = False
        await self._db.commit()
        return {"status": "ok"}

    async def update_book(self, book_id: str, user_id: str, title: str) -> dict:
        book = await self._db.get(Book, book_id)
        if not book:
            raise HTTPException(status_code=404, detail="Book not found")
        if book.user_id != user_id:
            raise HTTPException(status_code=403, detail="无权更新此回忆录")
        book.title = title
        await self._db.commit()
        await self._db.refresh(book)
        return {
            "id": book.id,
            "title": book.title,
            "total_pages": book.total_pages,
            "total_words": book.total_words,
            "cover_image_url": book.cover_image_url,
            "has_update": book.has_update,
            "last_update_chapter_id": book.last_update_chapter_id,
        }

    async def export_pdf(self, user_id: str, book_id: str) -> dict:
        from app.features.memoir.pdf_service import pdf_service

        book = await self._db.get(Book, book_id)
        if not book:
            raise HTTPException(status_code=404, detail="Book not found")
        if book.user_id != user_id:
            raise HTTPException(status_code=403, detail="无权导出此回忆录")
        stmt = (
            select(Chapter)
            .where(Chapter.user_id == user_id, Chapter.is_active == True)
            .options(
                joinedload(Chapter.images),
                joinedload(Chapter.story_links).joinedload(ChapterStoryLink.story),
            )
            .order_by(Chapter.order_index)
        )
        result = await self._db.execute(stmt)
        chapters = list(result.unique().scalars().all())
        asset_ids = collect_asset_ids_for_chapters(chapters)
        asset_map = await signed_urls_for_asset_ids(self._db, asset_ids)
        pdf_bytes = await pdf_service.generate_pdf(
            book, chapters, asset_url_map=asset_map
        )
        return {
            "pdf_base64": pdf_bytes.decode("latin1"),
            "filename": f"{book.title}.pdf",
        }

    async def get_chapters(
        self, user_id: str, is_new: bool | None = None
    ) -> List[dict]:
        chapters = await repo.get_chapters_with_sections(
            user_id, self._db, is_new_only=is_new
        )
        asset_ids: set[str] = set()
        for ch in chapters:
            asset_ids |= collect_asset_ids_for_chapter(ch)
        asset_map = await signed_urls_for_asset_ids(self._db, asset_ids)
        chapter_by_category: dict[str, Chapter] = {}
        for ch in chapters:
            if ch.category and ch.category not in chapter_by_category:
                chapter_by_category[ch.category] = ch
        all_chapters: List[dict] = []
        for category in CHAPTER_ORDER:
            ch = chapter_by_category.pop(category, None)
            if ch:
                await self._cleanup_unavailable_images(ch)
                all_chapters.append(chapter_to_list_dict(ch, asset_url_map=asset_map))
            else:
                if is_new is True:
                    continue
                all_chapters.append(
                    {
                        "id": f"placeholder_{category}",
                        "title": CHAPTER_CATEGORIES[category],
                        "category": category,
                        "order_index": STAGE_TO_ORDER.get(category, 999),
                        "status": "empty",
                        "summary": "",
                        "canonical_markdown": "",
                        "content": "",
                        "cover_asset": None,
                        "cover_image": None,
                        "images": [],
                        "sections": [],
                        "word_count": 0,
                        "updated_at": None,
                        "is_new": False,
                        "source_segments": [],
                    }
                )
        for ch in chapter_by_category.values():
            await self._cleanup_unavailable_images(ch)
            all_chapters.append(chapter_to_list_dict(ch, asset_url_map=asset_map))
        return all_chapters

    async def get_chapter(self, chapter_id: str, user_id: str) -> dict:
        chapter = await repo.get_chapter_by_id(chapter_id, self._db)
        if not chapter:
            raise HTTPException(status_code=404, detail="Chapter not found")
        if chapter.user_id != user_id:
            raise HTTPException(status_code=403, detail="无权访问此章节")
        if not chapter.is_active:
            raise HTTPException(status_code=404, detail="Chapter not found")
        await self._cleanup_unavailable_images(chapter)
        asset_map = await signed_urls_for_asset_ids(
            self._db, collect_asset_ids_for_chapter(chapter)
        )
        return chapter_to_dict(chapter, asset_url_map=asset_map)

    async def disable_chapter(self, chapter_id: str, user_id: str) -> dict:
        chapter = await repo.get_chapter_by_id(chapter_id, self._db)
        if not chapter:
            raise HTTPException(status_code=404, detail="Chapter not found")
        if chapter.user_id != user_id:
            raise HTTPException(status_code=403, detail="无权操作此章节")
        cos_keys = await repo.collect_cos_storage_keys_for_chapter(self._db, chapter)
        chapter.is_active = False
        await self._db.commit()
        delete_object_storage_keys_best_effort(
            self._object_storage,
            cos_keys,
            log_prefix=f"chapter_soft_delete id={chapter_id}",
        )
        return {"status": "ok", "message": "章节已清除"}

    async def regenerate_chapter(self, chapter_id: str, user_id: str) -> dict:
        chapter = await self._db.get(Chapter, chapter_id)
        if not chapter:
            raise HTTPException(status_code=404, detail="Chapter not found")
        if chapter.user_id != user_id:
            raise HTTPException(status_code=403, detail="无权操作此章节")
        n = await repo.count_chapter_story_links(self._db, chapter_id)
        if n > 0:
            raise HTTPException(
                status_code=400,
                detail="该章节由故事编排驱动，请更新故事正文或调整故事顺序，不支持在此处整章再生。",
            )
        # TODO: 非 story-backed 章节的 LLM 重新整理
        return {"status": "ok", "message": "Chapter regeneration triggered"}

    async def set_chapter_story_order(
        self, chapter_id: str, user_id: str, story_ids: list[str]
    ) -> dict:
        chapter = await self._db.get(Chapter, chapter_id)
        if not chapter:
            raise HTTPException(status_code=404, detail="Chapter not found")
        if chapter.user_id != user_id:
            raise HTTPException(status_code=403, detail="无权操作此章节")
        if not chapter.is_active:
            raise HTTPException(status_code=404, detail="Chapter not found")
        try:
            await repo.replace_chapter_story_links_async(
                self._db,
                chapter_id=chapter_id,
                user_id=user_id,
                story_ids=story_ids,
            )
        except ValueError as exc:
            raise HTTPException(status_code=400, detail=str(exc)) from exc

        ch = await repo.get_chapter_with_story_links_for_compose(chapter_id, self._db)
        if not ch:
            raise HTTPException(status_code=404, detail="Chapter not found")
        if not ch.story_links:
            md = ""
        else:
            md = materialize_chapter_markdown_from_loaded_chapter(ch)
        await repo.append_chapter_compose_version_async(self._db, ch, md)
        await self._db.commit()
        return {"status": "ok", "chapter_id": chapter_id, "story_count": len(story_ids)}

    async def get_memoir_state(self, user_id: str) -> dict:
        from app.features.memoir.state_service import get_or_create_state

        state = await get_or_create_state(user_id, self._db)
        return state.model_dump()

    async def get_next_question_context(self, user_id: str) -> dict:
        from app.features.memoir.state_service import get_or_create_state

        state = await get_or_create_state(user_id, self._db)
        return {
            "current_stage": state.current_stage,
            "empty_slots": state.empty_slots_for_current_stage(),
            "covered_stages": state.covered_stages,
        }

    async def check_and_trigger_cover_generation(self, user_id: str) -> dict:
        """
        有正文、尚无 cover_asset、且 legacy 封面 MemoirImage 未 completed 时，
        派发 generate_chapter_cover（由 intent/asset 闭环完成）。
        """
        from app.tasks.chapter_cover_enqueue import try_enqueue_generate_chapter_cover

        img_settings = MemoirImageSettings.from_env()
        if not img_settings.enabled:
            return {"triggered": []}

        chapters = await repo.get_chapters_with_sections(
            user_id, self._db, active_only=True, is_new_only=None
        )
        triggered: List[str] = []
        for ch in chapters:
            if not ch.category or ch.status == "empty":
                continue
            if getattr(ch, "cover_asset_id", None):
                continue
            md = (ch.canonical_markdown or "").strip()
            body = strip_legacy_image_placeholders(md).strip() if md else ""
            if not body:
                continue
            cover_rec = primary_chapter_memoir_image(ch)
            if cover_rec and (cover_rec.status or "").strip() == "completed":
                continue
            enqueued = await asyncio.to_thread(
                try_enqueue_generate_chapter_cover, ch.id, "http"
            )
            if enqueued:
                triggered.append(ch.id)
                logger.info("触发生成章节封面(asset): chapter=%s", ch.id)
        return {"triggered": triggered}

    async def mark_memoir_read(self, user_id: str) -> dict:
        stmt = select(Chapter).where(Chapter.user_id == user_id, Chapter.is_new == True)
        result = await self._db.execute(stmt)
        for chapter in result.scalars().all():
            chapter.is_new = False
        stmt_book = (
            select(Book).where(Book.user_id == user_id).order_by(Book.updated_at.desc())
        )
        result_book = await self._db.execute(stmt_book)
        book = result_book.scalar_one_or_none()
        if book:
            book.has_update = False
        await self._db.commit()
        return {"status": "ok"}