"""
Document Template API (MVP)

Endpoints:
- POST /api/templates/upload
- GET /api/templates/search
- GET /api/templates/{id}
- POST /api/templates/{id}/versions
- GET /api/templates/{id}/versions
- POST /api/templates/{id}/preview
"""
from __future__ import annotations

from typing import List, Optional, Dict, Any
from fastapi import APIRouter, Depends, HTTPException, status, UploadFile, File, Form, Query
from sqlalchemy.orm import Session
from sqlalchemy import func, or_, exists
import hashlib

from app.database.base import get_db
from app.auth.security import get_current_user
from app.models.user import User
from app.models.templates import DocumentTemplate, DocumentTemplateVersion, TemplateKeyword
from app.services.storage import get_default_storage
from app.services.template_merge import extract_tokens_from_bytes, build_context, resolve_tokens, render_docx


router = APIRouter()


from pydantic import BaseModel, Field


class TemplateResponse(BaseModel):
    id: int
    name: str
    description: Optional[str] = None
    category: Optional[str] = None
    active: bool
    current_version_id: Optional[int] = None


class VersionResponse(BaseModel):
    id: int
    template_id: int
    semantic_version: str
    mime_type: str
    size: int
    checksum: str
    changelog: Optional[str] = None
    is_approved: bool


class SearchResponseItem(BaseModel):
    id: int
    name: str
    category: Optional[str] = None
    active: bool
    latest_version: Optional[str] = None


class KeywordsRequest(BaseModel):
    keywords: List[str]


class KeywordsResponse(BaseModel):
    keywords: List[str]


class PreviewRequest(BaseModel):
    context: Dict[str, Any] = Field(default_factory=dict)
    version_id: Optional[int] = None


class PreviewResponse(BaseModel):
    resolved: Dict[str, Any]
    unresolved: List[str]
    output_mime_type: str
    output_size: int


class CategoryCount(BaseModel):
    category: Optional[str] = None
    count: int


@router.post("/upload", response_model=TemplateResponse)
async def upload_template(
    name: str = Form(...),
    category: Optional[str] = Form("GENERAL"),
    description: Optional[str] = Form(None),
    semantic_version: str = Form("1.0.0"),
    file: UploadFile = File(...),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    if file.content_type not in {"application/vnd.openxmlformats-officedocument.wordprocessingml.document", "application/pdf"}:
        raise HTTPException(status_code=400, detail="Only .docx or .pdf templates are supported")

    content = await file.read()
    if not content:
        raise HTTPException(status_code=400, detail="No file uploaded")

    sha256 = hashlib.sha256(content).hexdigest()
    storage = get_default_storage()
    storage_path = storage.save_bytes(content=content, filename_hint=file.filename or "template.bin", subdir="templates")

    template = DocumentTemplate(name=name, description=description, category=category, active=True, created_by=getattr(current_user, "username", None))
    db.add(template)
    db.flush()  # get id

    version = DocumentTemplateVersion(
        template_id=template.id,
        semantic_version=semantic_version,
        storage_path=storage_path,
        mime_type=file.content_type,
        size=len(content),
        checksum=sha256,
        changelog=None,
        created_by=getattr(current_user, "username", None),
        is_approved=True,
    )
    db.add(version)
    db.flush()
    template.current_version_id = version.id
    db.commit()
    db.refresh(template)

    return TemplateResponse(
        id=template.id,
        name=template.name,
        description=template.description,
        category=template.category,
        active=template.active,
        current_version_id=template.current_version_id,
    )


@router.get("/search", response_model=List[SearchResponseItem])
async def search_templates(
    q: Optional[str] = None,
    category: Optional[List[str]] = Query(
        None,
        description=(
            "Filter by category. Repeat the parameter (e.g., ?category=A&category=B) "
            "or pass a comma-separated list (e.g., ?category=A,B)."
        ),
    ),
    keywords: Optional[List[str]] = Query(None),
    keywords_mode: str = Query("any", description="Keyword match mode: any|all (default any)"),
    has_keywords: Optional[bool] = Query(
        None,
        description=(
            "When true, only templates that have one or more keywords are returned; "
            "when false, only templates with no keywords are returned."
        ),
    ),
    skip: int = Query(0, ge=0),
    limit: int = Query(50, ge=1, le=200),
    sort_by: Optional[str] = Query("name", description="Sort by: name | category | updated"),
    sort_dir: Optional[str] = Query("asc", description="Sort direction: asc or desc"),
    active_only: bool = Query(True, description="When true (default), only active templates are returned"),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    query = db.query(DocumentTemplate)
    if active_only:
        query = query.filter(DocumentTemplate.active == True)
    if q:
        like = f"%{q}%"
        query = query.filter(
            or_(
                DocumentTemplate.name.ilike(like),
                DocumentTemplate.description.ilike(like),
            )
        )
    # Category filtering (supports repeatable param and CSV within each value)
    if category:
        raw_values = category or []
        categories: List[str] = []
        for value in raw_values:
            parts = [part.strip() for part in (value or "").split(",")]
            for part in parts:
                if part:
                    categories.append(part)
        unique_categories = sorted(set(categories))
        if unique_categories:
            query = query.filter(DocumentTemplate.category.in_(unique_categories))
    if keywords:
        normalized = [kw.strip().lower() for kw in keywords if kw and kw.strip()]
        unique_keywords = sorted(set(normalized))
        if unique_keywords:
            mode = (keywords_mode or "any").lower()
            if mode not in ("any", "all"):
                mode = "any"
            query = query.join(TemplateKeyword, TemplateKeyword.template_id == DocumentTemplate.id)
            if mode == "any":
                query = query.filter(TemplateKeyword.keyword.in_(unique_keywords)).distinct()
            else:
                query = query.filter(TemplateKeyword.keyword.in_(unique_keywords))
                query = query.group_by(DocumentTemplate.id)
                query = query.having(func.count(func.distinct(TemplateKeyword.keyword)) == len(unique_keywords))
    # Has keywords filter (independent of specific keyword matches)
    if has_keywords is not None:
        kw_exists = exists().where(TemplateKeyword.template_id == DocumentTemplate.id)
        if has_keywords:
            query = query.filter(kw_exists)
        else:
            query = query.filter(~kw_exists)
    # Sorting
    sort_key = (sort_by or "name").lower()
    direction = (sort_dir or "asc").lower()
    if sort_key not in ("name", "category", "updated"):
        sort_key = "name"
    if direction not in ("asc", "desc"):
        direction = "asc"

    if sort_key == "name":
        order_col = DocumentTemplate.name
    elif sort_key == "category":
        order_col = DocumentTemplate.category
    else:  # updated
        order_col = func.coalesce(DocumentTemplate.updated_at, DocumentTemplate.created_at)

    if direction == "asc":
        query = query.order_by(order_col.asc())
    else:
        query = query.order_by(order_col.desc())

    # Pagination
    templates = query.offset(skip).limit(limit).all()
    items: List[SearchResponseItem] = []
    for tpl in templates:
        latest_version = None
        if tpl.current_version_id:
            ver = db.query(DocumentTemplateVersion).filter(DocumentTemplateVersion.id == tpl.current_version_id).first()
            if ver:
                latest_version = ver.semantic_version
        items.append(
            SearchResponseItem(
                id=tpl.id,
                name=tpl.name,
                category=tpl.category,
                active=tpl.active,
                latest_version=latest_version,
            )
        )
    return items


@router.get("/categories", response_model=List[CategoryCount])
async def list_template_categories(
    active_only: bool = Query(True, description="When true (default), only active templates are counted"),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    query = db.query(DocumentTemplate.category, func.count(DocumentTemplate.id).label("count"))
    if active_only:
        query = query.filter(DocumentTemplate.active == True)
    rows = query.group_by(DocumentTemplate.category).order_by(DocumentTemplate.category.asc()).all()
    return [CategoryCount(category=row[0], count=row[1]) for row in rows]


@router.get("/{template_id}", response_model=TemplateResponse)
async def get_template(
    template_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    tpl = db.query(DocumentTemplate).filter(DocumentTemplate.id == template_id).first()
    if not tpl:
        raise HTTPException(status_code=404, detail="Template not found")
    return TemplateResponse(
        id=tpl.id,
        name=tpl.name,
        description=tpl.description,
        category=tpl.category,
        active=tpl.active,
        current_version_id=tpl.current_version_id,
    )


@router.get("/{template_id}/versions", response_model=List[VersionResponse])
async def list_versions(
    template_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    versions = (
        db.query(DocumentTemplateVersion)
        .filter(DocumentTemplateVersion.template_id == template_id)
        .order_by(DocumentTemplateVersion.created_at.desc())
        .all()
    )
    return [
        VersionResponse(
            id=v.id,
            template_id=v.template_id,
            semantic_version=v.semantic_version,
            mime_type=v.mime_type,
            size=v.size,
            checksum=v.checksum,
            changelog=v.changelog,
            is_approved=v.is_approved,
        )
        for v in versions
    ]


@router.post("/{template_id}/versions", response_model=VersionResponse)
async def add_version(
    template_id: int,
    semantic_version: str = Form("1.0.0"),
    changelog: Optional[str] = Form(None),
    approve: bool = Form(True),
    file: UploadFile = File(...),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    tpl = db.query(DocumentTemplate).filter(DocumentTemplate.id == template_id).first()
    if not tpl:
        raise HTTPException(status_code=404, detail="Template not found")
    content = await file.read()
    if not content:
        raise HTTPException(status_code=400, detail="No file uploaded")
    sha256 = hashlib.sha256(content).hexdigest()
    storage = get_default_storage()
    storage_path = storage.save_bytes(content=content, filename_hint=file.filename or "template.bin", subdir="templates")
    version = DocumentTemplateVersion(
        template_id=template_id,
        semantic_version=semantic_version,
        storage_path=storage_path,
        mime_type=file.content_type,
        size=len(content),
        checksum=sha256,
        changelog=changelog,
        created_by=getattr(current_user, "username", None),
        is_approved=bool(approve),
    )
    db.add(version)
    db.flush()
    if approve:
        tpl.current_version_id = version.id
    db.commit()
    return VersionResponse(
        id=version.id,
        template_id=version.template_id,
        semantic_version=version.semantic_version,
        mime_type=version.mime_type,
        size=version.size,
        checksum=version.checksum,
        changelog=version.changelog,
        is_approved=version.is_approved,
    )


@router.post("/{template_id}/preview", response_model=PreviewResponse)
async def preview_template(
    template_id: int,
    payload: PreviewRequest,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    tpl = db.query(DocumentTemplate).filter(DocumentTemplate.id == template_id).first()
    if not tpl:
        raise HTTPException(status_code=404, detail="Template not found")
    version_id = payload.version_id or tpl.current_version_id
    if not version_id:
        raise HTTPException(status_code=400, detail="Template has no versions")
    ver = db.query(DocumentTemplateVersion).filter(DocumentTemplateVersion.id == version_id).first()
    if not ver:
        raise HTTPException(status_code=404, detail="Version not found")

    storage = get_default_storage()
    content = storage.open_bytes(ver.storage_path)
    tokens = extract_tokens_from_bytes(content)
    context = build_context(payload.context or {})
    resolved, unresolved = resolve_tokens(db, tokens, context)

    output_bytes = content
    output_mime = ver.mime_type
    if ver.mime_type == "application/vnd.openxmlformats-officedocument.wordprocessingml.document":
        output_bytes = render_docx(content, resolved)
        output_mime = ver.mime_type

    # We don't store preview output; just return metadata and resolution state
    return PreviewResponse(
        resolved=resolved,
        unresolved=unresolved,
        output_mime_type=output_mime,
        output_size=len(output_bytes),
    )


@router.get("/{template_id}/keywords", response_model=KeywordsResponse)
async def list_keywords(
    template_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    tpl = db.query(DocumentTemplate).filter(DocumentTemplate.id == template_id).first()
    if not tpl:
        raise HTTPException(status_code=404, detail="Template not found")
    kws = (
        db.query(TemplateKeyword)
        .filter(TemplateKeyword.template_id == template_id)
        .order_by(TemplateKeyword.keyword.asc())
        .all()
    )
    return KeywordsResponse(keywords=[k.keyword for k in kws])


@router.post("/{template_id}/keywords", response_model=KeywordsResponse)
async def add_keywords(
    template_id: int,
    payload: KeywordsRequest,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    tpl = db.query(DocumentTemplate).filter(DocumentTemplate.id == template_id).first()
    if not tpl:
        raise HTTPException(status_code=404, detail="Template not found")
    to_add = []
    for kw in (payload.keywords or []):
        normalized = (kw or "").strip().lower()
        if not normalized:
            continue
        exists = (
            db.query(TemplateKeyword)
            .filter(TemplateKeyword.template_id == template_id, TemplateKeyword.keyword == normalized)
            .first()
        )
        if not exists:
            to_add.append(TemplateKeyword(template_id=template_id, keyword=normalized))
    if to_add:
        db.add_all(to_add)
        db.commit()
    kws = (
        db.query(TemplateKeyword)
        .filter(TemplateKeyword.template_id == template_id)
        .order_by(TemplateKeyword.keyword.asc())
        .all()
    )
    return KeywordsResponse(keywords=[k.keyword for k in kws])


@router.delete("/{template_id}/keywords/{keyword}", response_model=KeywordsResponse)
async def remove_keyword(
    template_id: int,
    keyword: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    tpl = db.query(DocumentTemplate).filter(DocumentTemplate.id == template_id).first()
    if not tpl:
        raise HTTPException(status_code=404, detail="Template not found")
    normalized = (keyword or "").strip().lower()
    if normalized:
        db.query(TemplateKeyword).filter(
            TemplateKeyword.template_id == template_id,
            TemplateKeyword.keyword == normalized,
        ).delete(synchronize_session=False)
        db.commit()
    kws = (
        db.query(TemplateKeyword)
        .filter(TemplateKeyword.template_id == template_id)
        .order_by(TemplateKeyword.keyword.asc())
        .all()
    )
    return KeywordsResponse(keywords=[k.keyword for k in kws])