package repository

import (
	"context"
	"errors"

	dbgen "Yimaru-Backend/gen/db"
	"Yimaru-Backend/internal/domain"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgtype"
)

func moduleToDomain(m dbgen.Module) domain.Module {
	out := domain.Module{
		ID:        m.ID,
		ProgramID: m.ProgramID,
		CourseID:  m.CourseID,
		Name:      m.Name,
	}
	out.Description = fromPgText(m.Description)
	out.Icon = fromPgText(m.Icon)
	out.CreatedAt = m.CreatedAt.Time
	if m.UpdatedAt.Valid {
		t := m.UpdatedAt.Time
		out.UpdatedAt = &t
	}
	out.SortOrder = int(m.SortOrder)
	return out
}

func (s *Store) CreateModule(ctx context.Context, programID, courseID int64, input domain.CreateModuleInput) (domain.Module, error) {
	if input.SortOrder != nil {
		q, tx, err := s.BeginTx(ctx)
		if err != nil {
			return domain.Module{}, err
		}
		defer func() { _ = tx.Rollback(ctx) }()
		target := int32(*input.SortOrder)
		if _, err := tx.Exec(ctx,
			`UPDATE modules SET sort_order = sort_order + 1 WHERE course_id = $1 AND sort_order >= $2`,
			courseID, target,
		); err != nil {
			return domain.Module{}, err
		}
		m, err := q.CreateModule(ctx, dbgen.CreateModuleParams{
			ProgramID:   programID,
			CourseID:    courseID,
			Name:        input.Name,
			Description: toPgText(input.Description),
			Icon:        toPgText(input.Icon),
			SortOrder:   pgtype.Int4{Int32: target, Valid: true},
		})
		if err != nil {
			return domain.Module{}, err
		}
		if err := tx.Commit(ctx); err != nil {
			return domain.Module{}, err
		}
		return moduleToDomain(m), nil
	}

	m, err := s.queries.CreateModule(ctx, dbgen.CreateModuleParams{
		ProgramID:   programID,
		CourseID:    courseID,
		Name:        input.Name,
		Description: toPgText(input.Description),
		Icon:        toPgText(input.Icon),
		SortOrder:   pgtype.Int4{Valid: false},
	})
	if err != nil {
		return domain.Module{}, err
	}
	return moduleToDomain(m), nil
}

func (s *Store) ListModuleIDsByCourse(ctx context.Context, courseID int64) ([]int64, error) {
	return s.queries.ListModuleIDsByCourse(ctx, courseID)
}

func (s *Store) GetModuleByID(ctx context.Context, id int64) (domain.Module, error) {
	m, err := s.queries.GetModuleByID(ctx, id)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return domain.Module{}, pgx.ErrNoRows
		}
		return domain.Module{}, err
	}
	out := moduleToDomain(dbgen.Module{
		ID:          m.ID,
		ProgramID:   m.ProgramID,
		CourseID:    m.CourseID,
		Name:        m.Name,
		Description: m.Description,
		Icon:        m.Icon,
		SortOrder:   m.SortOrder,
		CreatedAt:   m.CreatedAt,
		UpdatedAt:   m.UpdatedAt,
	})
	out.HasPractice = m.HasPractice
	return out, nil
}

func (s *Store) ListModulesByProgramAndCourse(ctx context.Context, programID, courseID int64, limit, offset int32) ([]domain.Module, int64, error) {
	rows, err := s.queries.ListModulesByProgramAndCourse(ctx, dbgen.ListModulesByProgramAndCourseParams{
		ProgramID: programID,
		CourseID:  courseID,
		Limit:     limit,
		Offset:    offset,
	})
	if err != nil {
		return nil, 0, err
	}
	if len(rows) == 0 {
		return []domain.Module{}, 0, nil
	}
	var total int64
	out := make([]domain.Module, 0, len(rows))
	for i, r := range rows {
		if i == 0 {
			total = r.TotalCount
		}
		mod := moduleToDomain(dbgen.Module{
			ID:          r.ID,
			ProgramID:   r.ProgramID,
			CourseID:    r.CourseID,
			Name:        r.Name,
			Description: r.Description,
			Icon:        r.Icon,
			CreatedAt:   r.CreatedAt,
			UpdatedAt:   r.UpdatedAt,
			SortOrder:   r.SortOrder,
		})
		mod.HasPractice = r.HasPractice
		out = append(out, mod)
	}
	return out, total, nil
}

func (s *Store) UpdateModule(ctx context.Context, id int64, input domain.UpdateModuleInput) (domain.Module, error) {
	cur, err := s.GetModuleByID(ctx, id)
	if err != nil {
		return domain.Module{}, err
	}

	q, tx, err := s.BeginTx(ctx)
	if err != nil {
		return domain.Module{}, err
	}
	defer func() { _ = tx.Rollback(ctx) }()

	sortParam := optionalInt4Update(input.SortOrder)
	if input.SortOrder != nil {
		oldPos := int32(cur.SortOrder)
		newPos := int32(*input.SortOrder)
		if oldPos != newPos {
			if err := repositionModuleSortOrder(ctx, tx, cur.CourseID, id, oldPos, newPos); err != nil {
				return domain.Module{}, err
			}
		}
		sortParam = pgtype.Int4{Valid: false}
	}

	var nameText pgtype.Text
	if input.Name != nil {
		nameText = pgtype.Text{String: *input.Name, Valid: true}
	} else {
		nameText = pgtype.Text{Valid: false}
	}
	m, err := q.UpdateModule(ctx, dbgen.UpdateModuleParams{
		ID:          id,
		Name:        nameText,
		Description: optionalTextUpdate(input.Description),
		Icon:        optionalTextUpdate(input.Icon),
		SortOrder:   sortParam,
	})
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return domain.Module{}, pgx.ErrNoRows
		}
		return domain.Module{}, err
	}

	if err := tx.Commit(ctx); err != nil {
		return domain.Module{}, err
	}
	out := moduleToDomain(m)
	out.HasPractice = cur.HasPractice
	return out, nil
}

func (s *Store) DeleteModule(ctx context.Context, id int64) error {
	return s.queries.DeleteModule(ctx, id)
}