"""
课程服务层
"""
from typing import Optional, List, Dict, Any
from datetime import datetime

from sqlalchemy import select, or_, and_, func
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload

from app.core.logger import get_logger
from app.core.exceptions import NotFoundError, BadRequestError, ConflictError
from app.models.course import (
    Course,
    CourseStatus,
    CourseMaterial,
    KnowledgePoint,
    GrowthPath,
)
from app.models.course_exam_settings import CourseExamSettings
from app.models.position_member import PositionMember
from app.models.position_course import PositionCourse
from app.schemas.course import (
    CourseCreate,
    CourseUpdate,
    CourseList,
    CourseInDB,
    CourseMaterialCreate,
    KnowledgePointCreate,
    KnowledgePointUpdate,
    KnowledgePointInDB,
    GrowthPathCreate,
)
from app.schemas.base import PaginationParams, PaginatedResponse
from app.services.base_service import BaseService

logger = get_logger(__name__)


class CourseService(BaseService[Course]):
    """
    课程服务类
    """

    def __init__(self):
        super().__init__(Course)

    async def get_course_list(
        self,
        db: AsyncSession,
        *,
        page_params: PaginationParams,
        filters: CourseList,
        user_id: Optional[int] = None,
    ) -> PaginatedResponse[CourseInDB]:
        """
        获取课程列表（支持筛选）

        Args:
            db: 数据库会话
            page_params: 分页参数
            filters: 筛选条件
            user_id: 用户ID（用于记录访问日志）

        Returns:
            分页的课程列表
        """
        # 构建筛选条件
        filter_conditions = []

        # 状态筛选（默认只显示已发布的课程）
        if filters.status is not None:
            filter_conditions.append(Course.status == filters.status)
        else:
            # 如果没有指定状态，默认只返回已发布的课程
            filter_conditions.append(Course.status == CourseStatus.PUBLISHED)

        # 分类筛选
        if filters.category is not None:
            filter_conditions.append(Course.category == filters.category)

        # 是否推荐筛选
        if filters.is_featured is not None:
            filter_conditions.append(Course.is_featured == filters.is_featured)

        # 关键词搜索
        if filters.keyword:
            keyword = f"%{filters.keyword}%"
            filter_conditions.append(
                or_(Course.name.like(keyword), Course.description.like(keyword))
            )

        # 记录查询日志
        logger.info(
            "查询课程列表",
            user_id=user_id,
            filters=filters.model_dump(exclude_none=True),
            page=page_params.page,
            size=page_params.page_size,
        )

        # 执行分页查询
        query = select(Course).where(Course.is_deleted == False)

        # 添加筛选条件
        if filter_conditions:
            query = query.where(and_(*filter_conditions))

        # 添加排序：优先按sort_order升序，其次按创建时间降序（新课程优先）
        query = query.order_by(Course.sort_order.asc(), Course.created_at.desc())

        # 获取总数
        count_query = (
            select(func.count()).select_from(Course).where(Course.is_deleted == False)
        )
        if filter_conditions:
            count_query = count_query.where(and_(*filter_conditions))

        total_result = await db.execute(count_query)
        total = total_result.scalar() or 0

        # 分页
        query = query.offset(page_params.offset).limit(page_params.limit)
        query = query.options(selectinload(Course.materials))

        # 执行查询
        result = await db.execute(query)
        courses = result.scalars().all()

        # 获取用户所属的岗位ID列表
        user_position_ids = []
        if user_id:
            position_result = await db.execute(
                select(PositionMember.position_id).where(
                    PositionMember.user_id == user_id,
                    PositionMember.is_deleted == False
                )
            )
            user_position_ids = [row[0] for row in position_result.fetchall()]
        
        # 批量查询课程的岗位分配信息
        course_ids = [c.id for c in courses]
        course_type_map = {}
        if course_ids and user_position_ids:
            position_course_result = await db.execute(
                select(PositionCourse.course_id, PositionCourse.course_type).where(
                    PositionCourse.course_id.in_(course_ids),
                    PositionCourse.position_id.in_(user_position_ids),
                    PositionCourse.is_deleted == False
                )
            )
            # 构建课程类型映射：如果有多个岗位，优先取required
            for course_id, course_type in position_course_result.fetchall():
                if course_id not in course_type_map:
                    course_type_map[course_id] = course_type
                elif course_type == 'required':
                    course_type_map[course_id] = 'required'

        # 转换为 Pydantic 模型，并附加课程类型
        course_list = []
        for course in courses:
            course_data = CourseInDB.model_validate(course)
            # 设置课程类型：如果用户有岗位分配则使用分配类型，否则为None
            course_data.course_type = course_type_map.get(course.id)
            course_list.append(course_data)

        # 计算总页数
        pages = (total + page_params.page_size - 1) // page_params.page_size

        return PaginatedResponse(
            items=course_list,
            total=total,
            page=page_params.page,
            page_size=page_params.page_size,
            pages=pages,
        )

    async def create_course(
        self, db: AsyncSession, *, course_in: CourseCreate, created_by: int
    ) -> Course:
        """
        创建课程

        Args:
            db: 数据库会话
            course_in: 课程创建数据
            created_by: 创建人ID

        Returns:
            创建的课程
        """
        # 检查名称是否重复
        existing = await db.execute(
            select(Course).where(
                and_(Course.name == course_in.name, Course.is_deleted == False)
            )
        )
        existing_course = existing.scalar_one_or_none()
        if existing_course:
            raise ConflictError(
                f"课程名称 '{course_in.name}' 已存在",
                detail={"existing_id": existing_course.id, "existing_name": existing_course.name}
            )

        # 创建课程
        course_data = course_in.model_dump()
        course = await self.create(db, obj_in=course_data, created_by=created_by)

        # 自动创建默认考试设置
        default_exam_settings = CourseExamSettings(
            course_id=course.id,
            created_by=created_by,
            updated_by=created_by
            # 其他字段使用模型定义的默认值：
            # single_choice_count=4, multiple_choice_count=2, true_false_count=1,
            # fill_blank_count=2, essay_count=1, duration_minutes=10, 等
        )
        db.add(default_exam_settings)
        await db.commit()
        await db.refresh(course)

        logger.info(
            "创建课程", course_id=course.id, course_name=course.name, created_by=created_by
        )
        logger.info(
            "自动创建默认考试设置", course_id=course.id, exam_settings_id=default_exam_settings.id
        )

        return course

    async def update_course(
        self,
        db: AsyncSession,
        *,
        course_id: int,
        course_in: CourseUpdate,
        updated_by: int,
    ) -> Course:
        """
        更新课程

        Args:
            db: 数据库会话
            course_id: 课程ID
            course_in: 课程更新数据
            updated_by: 更新人ID

        Returns:
            更新后的课程
        """
        # 获取课程
        course = await self.get_by_id(db, course_id)
        if not course:
            raise NotFoundError(f"课程ID {course_id} 不存在")

        # 检查名称是否重复（如果修改了名称）
        if course_in.name and course_in.name != course.name:
            existing = await db.execute(
                select(Course).where(
                    and_(
                        Course.name == course_in.name,
                        Course.id != course_id,
                        Course.is_deleted == False,
                    )
                )
            )
            existing_course = existing.scalar_one_or_none()
            if existing_course:
                raise ConflictError(
                    f"课程名称 '{course_in.name}' 已存在",
                    detail={"existing_id": existing_course.id, "existing_name": existing_course.name}
                )

        # 记录状态变更
        old_status = course.status

        # 更新课程
        update_data = course_in.model_dump(exclude_unset=True)

        # 如果状态变为已发布，记录发布时间
        if (
            update_data.get("status") == CourseStatus.PUBLISHED
            and old_status != CourseStatus.PUBLISHED
        ):
            update_data["published_at"] = datetime.now()
            update_data["publisher_id"] = updated_by

        course = await self.update(
            db, db_obj=course, obj_in=update_data, updated_by=updated_by
        )

        logger.info(
            "更新课程",
            course_id=course.id,
            course_name=course.name,
            old_status=old_status,
            new_status=course.status,
            updated_by=updated_by,
        )

        return course

    async def delete_course(
        self, db: AsyncSession, *, course_id: int, deleted_by: int
    ) -> bool:
        """
        删除课程（软删除 + 删除相关文件）

        Args:
            db: 数据库会话
            course_id: 课程ID
            deleted_by: 删除人ID

        Returns:
            是否删除成功
        """
        import shutil
        from pathlib import Path
        from app.core.config import settings
        
        course = await self.get_by_id(db, course_id)
        if not course:
            raise NotFoundError(f"课程ID {course_id} 不存在")

        # 放开删除限制：任意状态均可软删除，由业务方自行控制

        # 执行软删除（标记 is_deleted，记录删除时间），由审计日志记录操作者
        success = await self.soft_delete(db, id=course_id)

        if success:
            # 删除课程文件夹及其所有内容
            course_folder = Path(settings.UPLOAD_PATH) / "courses" / str(course_id)
            if course_folder.exists() and course_folder.is_dir():
                try:
                    shutil.rmtree(course_folder)
                    logger.info(
                        "删除课程文件夹成功",
                        course_id=course_id,
                        folder_path=str(course_folder),
                    )
                except Exception as e:
                    # 文件夹删除失败不影响业务流程，仅记录日志
                    logger.error(
                        "删除课程文件夹失败",
                        course_id=course_id,
                        folder_path=str(course_folder),
                        error=str(e),
                    )
            
            logger.warning(
                "删除课程",
                course_id=course_id,
                course_name=course.name,
                deleted_by=deleted_by,
                folder_deleted=course_folder.exists(),
            )

        return success

    async def add_course_material(
        self,
        db: AsyncSession,
        *,
        course_id: int,
        material_in: CourseMaterialCreate,
        created_by: int,
    ) -> CourseMaterial:
        """
        添加课程资料

        Args:
            db: 数据库会话
            course_id: 课程ID
            material_in: 资料创建数据
            created_by: 创建人ID

        Returns:
            创建的课程资料
        """
        # 检查课程是否存在
        course = await self.get_by_id(db, course_id)
        if not course:
            raise NotFoundError(f"课程ID {course_id} 不存在")

        # 创建资料
        material_data = material_in.model_dump()
        material_data.update({
            "course_id": course_id,
            "created_by": created_by,
            "updated_by": created_by
        })

        material = CourseMaterial(**material_data)
        db.add(material)
        await db.commit()
        await db.refresh(material)

        logger.info(
            "添加课程资料",
            course_id=course_id,
            material_id=material.id,
            material_name=material.name,
            file_type=material.file_type,
            file_size=material.file_size,
            created_by=created_by,
        )

        return material

    async def get_course_materials(
        self,
        db: AsyncSession,
        *,
        course_id: int,
    ) -> List[CourseMaterial]:
        """
        获取课程资料列表

        Args:
            db: 数据库会话
            course_id: 课程ID

        Returns:
            课程资料列表
        """
        # 确认课程存在
        course = await self.get_by_id(db, course_id)
        if not course:
            raise NotFoundError(f"课程ID {course_id} 不存在")

        stmt = (
            select(CourseMaterial)
            .where(
                CourseMaterial.course_id == course_id,
                CourseMaterial.is_deleted == False,
            )
            .order_by(CourseMaterial.sort_order.asc(), CourseMaterial.id.asc())
        )
        result = await db.execute(stmt)
        materials = result.scalars().all()

        logger.info(
            "查询课程资料列表", course_id=course_id, count=len(materials)
        )

        return materials

    async def delete_course_material(
        self,
        db: AsyncSession,
        *,
        course_id: int,
        material_id: int,
        deleted_by: int,
    ) -> bool:
        """
        删除课程资料（软删除 + 删除物理文件）

        Args:
            db: 数据库会话
            course_id: 课程ID
            material_id: 资料ID
            deleted_by: 删除人ID

        Returns:
            是否删除成功
        """
        import os
        from pathlib import Path
        from app.core.config import settings
        
        # 先确认课程存在
        course = await self.get_by_id(db, course_id)
        if not course:
            raise NotFoundError(f"课程ID {course_id} 不存在")

        # 查找资料并校验归属
        material_stmt = select(CourseMaterial).where(
            CourseMaterial.id == material_id,
            CourseMaterial.course_id == course_id,
            CourseMaterial.is_deleted == False,
        )
        result = await db.execute(material_stmt)
        material = result.scalar_one_or_none()
        if not material:
            raise NotFoundError(f"课程资料ID {material_id} 不存在或已删除")

        # 获取文件路径信息用于删除物理文件
        file_url = material.file_url
        
        # 软删除数据库记录
        material.is_deleted = True
        material.deleted_at = datetime.now()
        if hasattr(material, "deleted_by"):
            # 兼容存在该字段的表
            setattr(material, "deleted_by", deleted_by)

        db.add(material)
        await db.commit()

        # 删除物理文件
        if file_url and file_url.startswith("/static/uploads/"):
            try:
                # 从URL中提取相对路径
                relative_path = file_url.replace("/static/uploads/", "")
                file_path = Path(settings.UPLOAD_PATH) / relative_path
                
                # 检查文件是否存在并删除
                if file_path.exists() and file_path.is_file():
                    os.remove(file_path)
                    logger.info(
                        "删除物理文件成功",
                        file_path=str(file_path),
                        material_id=material_id,
                    )
            except Exception as e:
                # 物理文件删除失败不影响业务流程，仅记录日志
                logger.error(
                    "删除物理文件失败",
                    file_url=file_url,
                    material_id=material_id,
                    error=str(e),
                )

        logger.warning(
            "删除课程资料",
            course_id=course_id,
            material_id=material_id,
            deleted_by=deleted_by,
            file_deleted=file_url is not None,
        )
        return True

    async def get_material_knowledge_points(
        self, db: AsyncSession, material_id: int
    ) -> List[KnowledgePointInDB]:
        """获取资料关联的知识点列表"""
        
        # 获取资料信息
        result = await db.execute(
            select(CourseMaterial).where(
                CourseMaterial.id == material_id,
                CourseMaterial.is_deleted == False
            )
        )
        material = result.scalar_one_or_none()
        
        if not material:
            raise NotFoundError(f"资料ID {material_id} 不存在")
        
        # 直接查询关联到该资料的知识点
        query = select(KnowledgePoint).where(
            KnowledgePoint.material_id == material_id,
            KnowledgePoint.is_deleted == False
        ).order_by(KnowledgePoint.created_at.desc())
        
        result = await db.execute(query)
        knowledge_points = result.scalars().all()
        
        from app.schemas.course import KnowledgePointInDB
        return [KnowledgePointInDB.model_validate(kp) for kp in knowledge_points]

    async def add_material_knowledge_points(
        self, db: AsyncSession, material_id: int, knowledge_point_ids: List[int]
    ) -> List[KnowledgePointInDB]:
        """
        为资料添加知识点关联
        
        注意：自2025-09-27起，知识点直接通过material_id关联到资料，
        material_knowledge_points中间表已废弃。此方法将更新知识点的material_id字段。
        """
        # 验证资料是否存在
        result = await db.execute(
            select(CourseMaterial).where(
                CourseMaterial.id == material_id,
                CourseMaterial.is_deleted == False
            )
        )
        material = result.scalar_one_or_none()
        
        if not material:
            raise NotFoundError(f"资料ID {material_id} 不存在")
        
        # 验证知识点是否存在且属于同一课程
        result = await db.execute(
            select(KnowledgePoint).where(
                KnowledgePoint.id.in_(knowledge_point_ids),
                KnowledgePoint.course_id == material.course_id,
                KnowledgePoint.is_deleted == False
            )
        )
        valid_knowledge_points = result.scalars().all()
        
        if len(valid_knowledge_points) != len(knowledge_point_ids):
            raise BadRequestError("部分知识点不存在或不属于同一课程")
        
        # 更新知识点的material_id字段
        added_knowledge_points = []
        for kp in valid_knowledge_points:
            # 更新知识点的资料关联
            kp.material_id = material_id
            added_knowledge_points.append(kp)
        
        await db.commit()
        
        # 刷新对象以获取更新后的数据
        for kp in added_knowledge_points:
            await db.refresh(kp)
        
        from app.schemas.course import KnowledgePointInDB
        return [KnowledgePointInDB.model_validate(kp) for kp in added_knowledge_points]

    async def remove_material_knowledge_point(
        self, db: AsyncSession, material_id: int, knowledge_point_id: int
    ) -> bool:
        """
        移除资料的知识点关联（软删除知识点）
        
        注意：自2025-09-27起，知识点直接通过material_id关联到资料，
        material_knowledge_points中间表已废弃。此方法将软删除知识点。
        """
        # 查找知识点并验证归属
        result = await db.execute(
            select(KnowledgePoint).where(
                KnowledgePoint.id == knowledge_point_id,
                KnowledgePoint.material_id == material_id,
                KnowledgePoint.is_deleted == False
            )
        )
        knowledge_point = result.scalar_one_or_none()
        
        if not knowledge_point:
            raise NotFoundError(f"知识点ID {knowledge_point_id} 不存在或不属于该资料")
        
        # 软删除知识点
        knowledge_point.is_deleted = True
        knowledge_point.deleted_at = datetime.now()
        
        await db.commit()
        
        logger.info(
            "移除资料知识点关联",
            material_id=material_id,
            knowledge_point_id=knowledge_point_id,
        )
        
        return True


class KnowledgePointService(BaseService[KnowledgePoint]):
    """
    知识点服务类
    """

    def __init__(self):
        super().__init__(KnowledgePoint)

    async def get_knowledge_points_by_course(
        self, db: AsyncSession, *, course_id: int, material_id: Optional[int] = None
    ) -> List[KnowledgePoint]:
        """
        获取课程的知识点列表

        Args:
            db: 数据库会话
            course_id: 课程ID
            material_id: 资料ID（可选，用于筛选特定资料的知识点）

        Returns:
            知识点列表
        """
        query = select(KnowledgePoint).where(
            and_(
                KnowledgePoint.course_id == course_id,
                KnowledgePoint.is_deleted == False,
            )
        )

        if material_id is not None:
            query = query.where(KnowledgePoint.material_id == material_id)

        query = query.order_by(KnowledgePoint.created_at.desc())

        result = await db.execute(query)
        return result.scalars().all()

    async def create_knowledge_point(
        self,
        db: AsyncSession,
        *,
        course_id: int,
        point_in: KnowledgePointCreate,
        created_by: int,
    ) -> KnowledgePoint:
        """
        创建知识点

        Args:
            db: 数据库会话
            course_id: 课程ID
            point_in: 知识点创建数据
            created_by: 创建人ID

        Returns:
            创建的知识点
        """
        # 检查课程是否存在
        course_service = CourseService()
        course = await course_service.get_by_id(db, course_id)
        if not course:
            raise NotFoundError(f"课程ID {course_id} 不存在")

        # 创建知识点
        point_data = point_in.model_dump()
        point_data.update({"course_id": course_id})

        knowledge_point = await self.create(
            db, obj_in=point_data, created_by=created_by
        )

        logger.info(
            "创建知识点",
            course_id=course_id,
            knowledge_point_id=knowledge_point.id,
            knowledge_point_name=knowledge_point.name,
            created_by=created_by,
        )

        return knowledge_point

    async def update_knowledge_point(
        self,
        db: AsyncSession,
        *,
        point_id: int,
        point_in: KnowledgePointUpdate,
        updated_by: int,
    ) -> KnowledgePoint:
        """
        更新知识点

        Args:
            db: 数据库会话
            point_id: 知识点ID
            point_in: 知识点更新数据
            updated_by: 更新人ID

        Returns:
            更新后的知识点
        """
        knowledge_point = await self.get_by_id(db, point_id)
        if not knowledge_point:
            raise NotFoundError(f"知识点ID {point_id} 不存在")

        # 验证关联资料是否存在
        if hasattr(point_in, 'material_id') and point_in.material_id:
            result = await db.execute(
                select(CourseMaterial).where(
                    CourseMaterial.id == point_in.material_id,
                    CourseMaterial.is_deleted == False
                )
            )
            material = result.scalar_one_or_none()
            if not material:
                raise NotFoundError(f"资料ID {point_in.material_id} 不存在")

        # 更新知识点
        update_data = point_in.model_dump(exclude_unset=True)
        knowledge_point = await self.update(
            db, db_obj=knowledge_point, obj_in=update_data, updated_by=updated_by
        )

        logger.info(
            "更新知识点",
            knowledge_point_id=knowledge_point.id,
            knowledge_point_name=knowledge_point.name,
            updated_by=updated_by,
        )

        return knowledge_point


class GrowthPathService(BaseService[GrowthPath]):
    """
    成长路径服务类
    """

    def __init__(self):
        super().__init__(GrowthPath)

    async def create_growth_path(
        self, db: AsyncSession, *, path_in: GrowthPathCreate, created_by: int
    ) -> GrowthPath:
        """
        创建成长路径

        Args:
            db: 数据库会话
            path_in: 成长路径创建数据
            created_by: 创建人ID

        Returns:
            创建的成长路径
        """
        # 检查名称是否重复
        existing = await db.execute(
            select(GrowthPath).where(
                and_(GrowthPath.name == path_in.name, GrowthPath.is_deleted == False)
            )
        )
        existing_path = existing.scalar_one_or_none()
        if existing_path:
            raise ConflictError(
                f"成长路径名称 '{path_in.name}' 已存在",
                detail={"existing_id": existing_path.id, "existing_name": existing_path.name, "type": "growth_path"}
            )

        # 验证课程是否存在
        if path_in.courses:
            course_ids = [c.course_id for c in path_in.courses]
            course_service = CourseService()
            for course_id in course_ids:
                course = await course_service.get_by_id(db, course_id)
                if not course:
                    raise NotFoundError(f"课程ID {course_id} 不存在")

        # 创建成长路径
        path_data = path_in.model_dump()
        # 转换课程列表为JSON格式
        if path_data.get("courses"):
            path_data["courses"] = [c.model_dump() for c in path_in.courses]

        growth_path = await self.create(db, obj_in=path_data, created_by=created_by)

        logger.info(
            "创建成长路径",
            growth_path_id=growth_path.id,
            growth_path_name=growth_path.name,
            course_count=len(path_in.courses) if path_in.courses else 0,
            created_by=created_by,
        )

        return growth_path


# 创建服务实例
course_service = CourseService()
knowledge_point_service = KnowledgePointService()
growth_path_service = GrowthPathService()