import uuid
from datetime import datetime

from fastapi import APIRouter, Depends, HTTPException, Request
from sqlalchemy import delete, select, text
from sqlalchemy.ext.asyncio import AsyncSession

from app.database import get_db
from app.models.document import Document
from app.models.folder import Folder
from app.models.project import Project
from app.models.tag import DocumentTag, Tag
from app.routers.auth import get_current_agent
from app.schemas.document import (
    DocumentBriefResponse,
    DocumentContentUpdate,
    DocumentCreate,
    DocumentListResponse,
    DocumentResponse,
    DocumentUpdate,
    TagInfo,
)
from app.schemas.tag import DocumentTagsAssign


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


def build_doc_path(project_id: str, doc_id: str, folder_id: str | None, folder_path: str | None) -> str:
    if folder_id and folder_path:
        return f"{folder_path}/{doc_id}"
    return f"/{project_id}/{doc_id}"


async def get_document_tags(db: AsyncSession, doc_id: str) -> list[TagInfo]:
    result = await db.execute(
        text("""
            SELECT t.id, t.name, t.color
            FROM active_tags t
            JOIN document_tags dt ON t.id = dt.tag_id
            WHERE dt.document_id = :doc_id
        """),
        {"doc_id": doc_id}
    )
    rows = result.fetchall()
    return [TagInfo(id=r.id, name=r.name, color=r.color) for r in rows]


async def document_to_response(db: AsyncSession, doc: Document) -> DocumentResponse:
    tags = await get_document_tags(db, doc.id)
    return DocumentResponse(
        id=doc.id,
        title=doc.title,
        content=doc.content,
        project_id=doc.project_id,
        folder_id=doc.folder_id,
        path=doc.path,
        tags=tags,
        created_at=doc.created_at,
        updated_at=doc.updated_at,
    )


@router.get("/api/v1/projects/{project_id}/documents", response_model=DocumentListResponse)
async def list_documents(
    request: Request,
    project_id: str,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    proj_result = await db.execute(
        select(Project).where(
            Project.id == project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=404, detail="Project not found")

    result = await db.execute(
        select(Document).where(
            Document.project_id == project_id,
            Document.is_deleted == False,
        ).order_by(Document.created_at.desc())
    )
    docs = result.scalars().all()

    responses = []
    for doc in docs:
        tags = await get_document_tags(db, doc.id)
        responses.append(DocumentBriefResponse(
            id=doc.id,
            title=doc.title,
            project_id=doc.project_id,
            folder_id=doc.folder_id,
            path=doc.path,
            tags=tags,
            created_at=doc.created_at,
            updated_at=doc.updated_at,
        ))

    return DocumentListResponse(documents=responses)


@router.post("/api/v1/projects/{project_id}/documents", response_model=DocumentResponse, status_code=201)
async def create_document(
    request: Request,
    project_id: str,
    payload: DocumentCreate,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    proj_result = await db.execute(
        select(Project).where(
            Project.id == project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=404, detail="Project not found")

    folder_path = None
    if payload.folder_id:
        folder_result = await db.execute(
            select(Folder).where(
                Folder.id == payload.folder_id,
                Folder.project_id == project_id,
                Folder.is_deleted == False,
            )
        )
        folder = folder_result.scalar_one_or_none()
        if not folder:
            raise HTTPException(status_code=400, detail="Folder not found")
        folder_path = folder.path

    doc_id = str(uuid.uuid4())
    path = build_doc_path(project_id, doc_id, payload.folder_id, folder_path)

    doc = Document(
        id=doc_id,
        title=payload.title,
        content=payload.content,
        project_id=project_id,
        folder_id=payload.folder_id,
        path=path,
    )
    db.add(doc)
    await db.flush()
    return await document_to_response(db, doc)


@router.get("/api/v1/documents/{document_id}", response_model=DocumentResponse)
async def get_document(
    request: Request,
    document_id: str,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    result = await db.execute(
        select(Document).where(
            Document.id == document_id,
            Document.is_deleted == False,
        )
    )
    doc = result.scalar_one_or_none()
    if not doc:
        raise HTTPException(status_code=404, detail="Document not found")

    proj_result = await db.execute(
        select(Project).where(
            Project.id == doc.project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=404, detail="Document not found")

    return await document_to_response(db, doc)


@router.put("/api/v1/documents/{document_id}", response_model=DocumentResponse)
async def update_document(
    request: Request,
    document_id: str,
    payload: DocumentUpdate,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    result = await db.execute(
        select(Document).where(
            Document.id == document_id,
            Document.is_deleted == False,
        )
    )
    doc = result.scalar_one_or_none()
    if not doc:
        raise HTTPException(status_code=404, detail="Document not found")

    proj_result = await db.execute(
        select(Project).where(
            Project.id == doc.project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=403, detail="Forbidden")

    if payload.title is not None:
        doc.title = payload.title
    if payload.folder_id is not None:
        if payload.folder_id:
            folder_result = await db.execute(
                select(Folder).where(
                    Folder.id == payload.folder_id,
                    Folder.project_id == doc.project_id,
                    Folder.is_deleted == False,
                )
            )
            folder = folder_result.scalar_one_or_none()
            if not folder:
                raise HTTPException(status_code=400, detail="Folder not found")
            doc.path = f"{folder.path}/{doc.id}"
        else:
            doc.path = f"/{doc.project_id}/{doc.id}"
        doc.folder_id = payload.folder_id

    doc.updated_at = datetime.utcnow()
    await db.flush()
    return await document_to_response(db, doc)


@router.delete("/api/v1/documents/{document_id}", status_code=204)
async def delete_document(
    request: Request,
    document_id: str,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    result = await db.execute(
        select(Document).where(
            Document.id == document_id,
            Document.is_deleted == False,
        )
    )
    doc = result.scalar_one_or_none()
    if not doc:
        raise HTTPException(status_code=404, detail="Document not found")

    proj_result = await db.execute(
        select(Project).where(
            Project.id == doc.project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=403, detail="Forbidden")

    doc.is_deleted = True
    doc.deleted_at = datetime.utcnow()
    doc.deleted_by = agent.id
    await db.flush()
    return None


@router.put("/api/v1/documents/{document_id}/content", response_model=DocumentResponse)
async def update_document_content(
    request: Request,
    document_id: str,
    payload: DocumentContentUpdate,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    result = await db.execute(
        select(Document).where(
            Document.id == document_id,
            Document.is_deleted == False,
        )
    )
    doc = result.scalar_one_or_none()
    if not doc:
        raise HTTPException(status_code=404, detail="Document not found")

    proj_result = await db.execute(
        select(Project).where(
            Project.id == doc.project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=403, detail="Forbidden")

    doc.content = payload.content
    doc.updated_at = datetime.utcnow()
    await db.flush()
    return await document_to_response(db, doc)


@router.post("/api/v1/documents/{document_id}/restore", response_model=DocumentResponse)
async def restore_document(
    request: Request,
    document_id: str,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    result = await db.execute(
        select(Document).where(
            Document.id == document_id,
            Document.is_deleted == True,
        )
    )
    doc = result.scalar_one_or_none()
    if not doc:
        raise HTTPException(status_code=404, detail="Document not found")

    proj_result = await db.execute(
        select(Project).where(
            Project.id == doc.project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=403, detail="Forbidden")

    doc.is_deleted = False
    doc.deleted_at = None
    doc.deleted_by = None
    await db.flush()
    return await document_to_response(db, doc)


@router.post("/api/v1/documents/{document_id}/tags", status_code=204)
async def assign_tags(
    request: Request,
    document_id: str,
    payload: DocumentTagsAssign,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    result = await db.execute(
        select(Document).where(
            Document.id == document_id,
            Document.is_deleted == False,
        )
    )
    doc = result.scalar_one_or_none()
    if not doc:
        raise HTTPException(status_code=404, detail="Document not found")

    proj_result = await db.execute(
        select(Project).where(
            Project.id == doc.project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=403, detail="Forbidden")

    for tag_id in payload.tag_ids:
        tag_result = await db.execute(
            select(Tag).where(
                Tag.id == tag_id,
                Tag.is_deleted == False,
            )
        )
        tag = tag_result.scalar_one_or_none()
        if not tag:
            raise HTTPException(status_code=400, detail=f"Tag {tag_id} not found")

        existing = await db.execute(
            select(DocumentTag).where(
                DocumentTag.document_id == document_id,
                DocumentTag.tag_id == tag_id,
            )
        )
        if not existing.scalar_one_or_none():
            dt = DocumentTag(document_id=document_id, tag_id=tag_id)
            db.add(dt)

    await db.flush()
    return None


@router.delete("/api/v1/documents/{document_id}/tags/{tag_id}", status_code=204)
async def remove_tag(
    request: Request,
    document_id: str,
    tag_id: str,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    result = await db.execute(
        select(Document).where(
            Document.id == document_id,
            Document.is_deleted == False,
        )
    )
    doc = result.scalar_one_or_none()
    if not doc:
        raise HTTPException(status_code=404, detail="Document not found")

    proj_result = await db.execute(
        select(Project).where(
            Project.id == doc.project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=403, detail="Forbidden")

    await db.execute(
        delete(DocumentTag).where(
            DocumentTag.document_id == document_id,
            DocumentTag.tag_id == tag_id,
        )
    )
    await db.flush()
    return None