package model

import (
	"context"
	"time"

	"gorm.io/gorm"

	conventity "spark-server/internal/module/conversation/entity"
	convmodel "spark-server/internal/module/conversation/model"
	"spark-server/internal/module/group/entity"
	"spark-server/internal/pkg/errs"
)

func (m *Repo) CreateGroup(ctx context.Context, g *entity.Group, members []*entity.Member) error {
	if g == nil || g.ConversationID <= 0 || len(members) == 0 {
		return errs.ErrInvalidArgument
	}
	db, err := m.session(ctx)
	if err != nil {
		return err
	}
	now := msTime(g.CreatedAtMS)
	return db.Transaction(func(tx *gorm.DB) error {
		conv := convmodel.Conversation{
			ID: g.ConversationID, Type: conventity.TypeGroup, LastMsgAt: now, CreatedAt: now,
		}
		if err := tx.Create(&conv).Error; err != nil {
			return mapDBErr(err)
		}
		g.ID = 0
		g.MemberCount = len(members)
		row := groupRow(g)
		if err := tx.Create(row).Error; err != nil {
			return mapDBErr(err)
		}
		g.ID = row.ID
		for _, mem := range members {
			if mem == nil {
				continue
			}
			mem.GroupID = g.ID
			if err := insertMember(tx, mem, g.ConversationID, now); err != nil {
				return err
			}
		}
		return nil
	})
}

func (m *Repo) AddMembers(ctx context.Context, groupID int64, members []*entity.Member) error {
	if groupID <= 0 || len(members) == 0 {
		return errs.ErrInvalidArgument
	}
	db, err := m.session(ctx)
	if err != nil {
		return err
	}
	now := time.Now()
	return db.Transaction(func(tx *gorm.DB) error {
		g, err := takeActiveGroup(tx, groupID)
		if err != nil {
			return err
		}
		for _, mem := range members {
			if mem == nil {
				continue
			}
			mem.GroupID = groupID
			if err := insertMember(tx, mem, g.ConversationID, now); err != nil {
				return err
			}
		}
		return bumpMemberCount(tx, groupID, len(members), now)
	})
}

func (m *Repo) RemoveMember(ctx context.Context, groupID, userID int64) error {
	if groupID <= 0 || userID <= 0 {
		return errs.ErrInvalidArgument
	}
	db, err := m.session(ctx)
	if err != nil {
		return err
	}
	now := time.Now()
	return db.Transaction(func(tx *gorm.DB) error {
		g, err := takeActiveGroup(tx, groupID)
		if err != nil {
			return err
		}
		res := tx.Where("group_id = ? AND user_id = ?", groupID, userID).Delete(&GroupMember{})
		if res.Error != nil {
			return mapDBErr(res.Error)
		}
		if res.RowsAffected == 0 {
			return errs.ErrNotFound
		}
		if err := tx.Where("conversation_id = ? AND user_id = ?", g.ConversationID, userID).
			Delete(&convmodel.ConversationMember{}).Error; err != nil {
			return mapDBErr(err)
		}
		return bumpMemberCount(tx, groupID, -1, now)
	})
}

func (m *Repo) Dissolve(ctx context.Context, groupID int64) error {
	if groupID <= 0 {
		return errs.ErrInvalidArgument
	}
	db, err := m.session(ctx)
	if err != nil {
		return err
	}
	now := time.Now()
	return db.Transaction(func(tx *gorm.DB) error {
		g, err := takeActiveGroup(tx, groupID)
		if err != nil {
			return err
		}
		res := tx.Model(&Group{}).Where("id = ? AND status = ?", groupID, entity.StatusActive).Updates(map[string]any{
			"status":       entity.StatusDissolved,
			"member_count": 0,
			"updated_at":   now,
		})
		if res.Error != nil {
			return mapDBErr(res.Error)
		}
		if res.RowsAffected == 0 {
			return errs.ErrNotFound
		}
		if err := tx.Where("group_id = ?", groupID).Delete(&GroupMember{}).Error; err != nil {
			return mapDBErr(err)
		}
		if err := tx.Where("conversation_id = ?", g.ConversationID).Delete(&convmodel.ConversationMember{}).Error; err != nil {
			return mapDBErr(err)
		}
		return nil
	})
}

func (m *Repo) TransferOwner(ctx context.Context, groupID, fromID, toID int64) error {
	if groupID <= 0 || fromID <= 0 || toID <= 0 || fromID == toID {
		return errs.ErrInvalidArgument
	}
	db, err := m.session(ctx)
	if err != nil {
		return err
	}
	now := time.Now()
	return db.Transaction(func(tx *gorm.DB) error {
		res := tx.Model(&Group{}).Where("id = ? AND owner_id = ? AND status = ?", groupID, fromID, entity.StatusActive).
			Updates(map[string]any{"owner_id": toID, "updated_at": now})
		if res.Error != nil {
			return mapDBErr(res.Error)
		}
		if res.RowsAffected == 0 {
			return errs.ErrNotFound
		}
		if err := tx.Model(&GroupMember{}).Where("group_id = ? AND user_id = ?", groupID, fromID).
			Update("role", entity.RoleMember).Error; err != nil {
			return mapDBErr(err)
		}
		res = tx.Model(&GroupMember{}).Where("group_id = ? AND user_id = ?", groupID, toID).
			Updates(map[string]any{"role": entity.RoleOwner, "speak_muted": 0})
		if res.Error != nil {
			return mapDBErr(res.Error)
		}
		if res.RowsAffected == 0 {
			return errs.ErrNotFound
		}
		return nil
	})
}

func takeActiveGroup(tx *gorm.DB, groupID int64) (*Group, error) {
	var row Group
	if err := tx.Where("id = ? AND status = ?", groupID, entity.StatusActive).Take(&row).Error; err != nil {
		return nil, mapDBErr(err)
	}
	return &row, nil
}

func insertMember(tx *gorm.DB, mem *entity.Member, conversationID int64, now time.Time) error {
	if mem.JoinedAtMS <= 0 {
		mem.JoinedAtMS = now.UnixMilli()
	}
	if err := tx.Create(memberRow(mem)).Error; err != nil {
		return mapDBErr(err)
	}
	row := convmodel.ConversationMember{
		ConversationID: conversationID, UserID: mem.UserID, JoinedAt: msTime(mem.JoinedAtMS),
	}
	return mapDBErr(tx.Create(&row).Error)
}

func bumpMemberCount(tx *gorm.DB, groupID int64, delta int, now time.Time) error {
	res := tx.Model(&Group{}).Where("id = ? AND status = ?", groupID, entity.StatusActive).
		Updates(map[string]any{
			"member_count": gorm.Expr("member_count + ?", delta),
			"updated_at":   now,
		})
	if res.Error != nil {
		return mapDBErr(res.Error)
	}
	if res.RowsAffected == 0 {
		return errs.ErrNotFound
	}
	return nil
}