package postgres

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"git.aiterp.net/rpdata/api/database/postgres/psqlcore"
	"git.aiterp.net/rpdata/api/internal/generate"
	"git.aiterp.net/rpdata/api/models"
	"strings"
)

type postRepository struct {
	insertWithIDs bool
	db            *sql.DB
}

func (r *postRepository) Find(ctx context.Context, id string) (*models.Post, error) {
	post, err := psqlcore.New(r.db).SelectPost(ctx, id)
	if err != nil {
		return nil, err
	}

	return r.post(post), nil
}

func (r *postRepository) List(ctx context.Context, filter models.PostFilter) ([]*models.Post, error) {
	q := psqlcore.New(r.db)
	params := psqlcore.SelectPostsParams{LimitSize: 0}
	if filter.LogID != nil {
		params.FilterLogShortID = true

		if !strings.HasPrefix(*filter.LogID, "L") {
			log, err := q.SelectLog(ctx, *filter.LogID)
			if err != nil {
				return nil, err
			}

			params.LogShortID = log.ShortID
		} else {
			params.LogShortID = *filter.LogID
		}
	}
	if filter.Kinds != nil {
		params.FilterKinds = true
		params.Kinds = filter.Kinds
	}
	if filter.Search != nil {
		params.FilterSearch = true
		params.Search = TSQueryFromSearch(*filter.Search)
	}
	if filter.Limit > 0 {
		params.LimitSize = int32(filter.Limit)
	}

	posts, err := q.SelectPosts(ctx, params)
	if err != nil {
		return nil, err
	}

	return r.posts(posts), nil
}

func (r *postRepository) Insert(ctx context.Context, post models.Post) (*models.Post, error) {
	if !r.insertWithIDs || len(post.ID) < 8 {
		post.ID = generate.PostID()
	}

	position, err := psqlcore.New(r.db).InsertPost(ctx, psqlcore.InsertPostParams{
		ID:         post.ID,
		LogShortID: post.LogID,
		Time:       post.Time.UTC(),
		Kind:       post.Kind,
		Nick:       post.Nick,
		Text:       post.Text,
	})
	if err != nil {
		return nil, err
	}

	_ = psqlcore.New(r.db).GenerateLogTSVector(ctx, post.LogID)

	post.Position = int(position)

	return &post, nil
}

func (r *postRepository) InsertMany(ctx context.Context, posts ...*models.Post) ([]*models.Post, error) {
	if len(posts) == 0 {
		return []*models.Post{}, nil
	}

	allowedLogID := ""
	for _, post := range posts {
		if allowedLogID == "" {
			allowedLogID = post.LogID
		} else if allowedLogID != post.LogID {
			return nil, errors.New("cannot insert multiple posts with different log IDs")
		}
	}

	params := psqlcore.InsertPostsParams{
		LogShortID: posts[0].LogID,
	}

	for _, post := range posts {
		if !r.insertWithIDs || len(post.ID) < 8 {
			post.ID = generate.PostID()
		}

		params.Ids = append(params.Ids, post.ID)
		params.Kinds = append(params.Kinds, post.Kind)
		params.Nicks = append(params.Nicks, post.Nick)
		params.Offsets = append(params.Offsets, int32(len(params.Offsets)+1))
		params.Times = append(params.Times, post.Time.UTC())
		params.Texts = append(params.Texts, post.Text)
	}

	offset, err := psqlcore.New(r.db).InsertPosts(ctx, params)
	if err != nil {
		return nil, err
	}

	for i, post := range posts {
		post.Position = int(offset) + i
	}

	err = psqlcore.New(r.db).GenerateLogTSVector(ctx, posts[0].LogID)
	if err != nil {
		return nil, err
	}

	return posts, nil
}

func (r *postRepository) Update(ctx context.Context, post models.Post, update models.PostUpdate) (*models.Post, error) {
	post.ApplyUpdate(update)

	err := psqlcore.New(r.db).UpdatePost(ctx, psqlcore.UpdatePostParams{
		Time: post.Time,
		Kind: post.Kind,
		Nick: post.Nick,
		Text: post.Text,
		ID:   post.ID,
	})
	if err != nil {
		return nil, err
	}

	_ = psqlcore.New(r.db).GenerateLogTSVector(ctx, post.LogID)

	return &post, nil
}

func (r *postRepository) Move(ctx context.Context, post models.Post, position int) ([]*models.Post, error) {
	if position == post.Position {
		return r.List(ctx, models.PostFilter{LogID: &post.LogID})
	}

	tx, err := r.db.BeginTx(ctx, nil)
	if err != nil {
		return nil, err
	}
	defer func() { _ = tx.Rollback() }()

	_, err = tx.Exec("LOCK TABLE log_post IN SHARE UPDATE EXCLUSIVE MODE")
	if err != nil {
		return nil, err
	}

	var lowest, highest int32

	q := psqlcore.New(tx)

	err = q.MovePost(ctx, psqlcore.MovePostParams{ID: post.ID, Position: -1})
	if err != nil {
		return nil, err
	}

	if position > post.Position {
		lowest = int32(post.Position)
		highest = int32(position)

		err := q.ShiftPostsBetween(ctx, psqlcore.ShiftPostsBetweenParams{
			ShiftOffset:  -1,
			LogShortID:   post.LogID,
			FromPosition: lowest + 1,
			ToPosition:   highest,
		})
		if err != nil {
			return nil, err
		}
	} else {
		lowest = int32(position)
		highest = int32(post.Position)

		err := q.ShiftPostsBetween(ctx, psqlcore.ShiftPostsBetweenParams{
			ShiftOffset:  1,
			LogShortID:   post.LogID,
			FromPosition: lowest,
			ToPosition:   highest - 1,
		})
		if err != nil {
			return nil, err
		}
	}

	err = q.MovePost(ctx, psqlcore.MovePostParams{ID: post.ID, Position: int32(position)})
	if err != nil {
		return nil, err
	}

	posts, err := q.SelectPostsByPositionRange(ctx, psqlcore.SelectPostsByPositionRangeParams{
		LogShortID:   post.LogID,
		FromPosition: lowest,
		ToPosition:   highest,
	})
	if err != nil {
		return nil, err
	}

	positions, err := q.SelectPositionsByLogShortID(ctx, post.LogID)
	if err != nil {
		return nil, err
	}
	prev := int32(0)
	for _, pos := range positions {
		if pos != prev+1 {
			return nil, errors.New("post discontinuity detected")
		}

		prev = pos
	}

	err = tx.Commit()
	if err != nil {
		return nil, err
	}

	return r.posts2(posts), nil
}

func (r *postRepository) Delete(ctx context.Context, post models.Post) error {
	tx, err := r.db.BeginTx(ctx, nil)
	if err != nil {
		return err
	}
	defer func() { _ = tx.Rollback() }()
	q := psqlcore.New(tx)

	_, err = tx.Exec("LOCK TABLE log_post IN SHARE UPDATE EXCLUSIVE MODE")
	if err != nil {
		return err
	}

	err = q.MovePost(ctx, psqlcore.MovePostParams{ID: post.ID, Position: -1})
	if err != nil {
		return fmt.Errorf("pre-delete move failed: %s", err)
	}

	err = q.ShiftPostsAfter(ctx, psqlcore.ShiftPostsAfterParams{
		ShiftOffset:  -1,
		LogShortID:   post.LogID,
		FromPosition: int32(post.Position + 1),
	})
	if err != nil {
		return fmt.Errorf("shift failed: %s", err)
	}

	err = q.DeletePost(ctx, post.ID)
	if err != nil {
		return fmt.Errorf("delete failed: %s", err)
	}

	err = tx.Commit()
	if err != nil {
		return fmt.Errorf("tx commit failed: %s", err)
	}

	_ = psqlcore.New(r.db).GenerateLogTSVector(ctx, post.LogID)

	return nil
}

func (r *postRepository) post(post psqlcore.SelectPostRow) *models.Post {
	return &models.Post{
		ID:       post.ID,
		LogID:    post.LogShortID,
		Time:     post.Time,
		Kind:     post.Kind,
		Nick:     post.Nick,
		Text:     post.Text,
		Position: int(post.Position),
	}
}

func (r *postRepository) posts(posts []psqlcore.SelectPostsRow) []*models.Post {
	results := make([]*models.Post, 0, len(posts))
	for _, post := range posts {
		results = append(results, r.post(psqlcore.SelectPostRow(post)))
	}

	return results
}

func (r *postRepository) posts2(posts []psqlcore.SelectPostsByPositionRangeRow) []*models.Post {
	results := make([]*models.Post, 0, len(posts))
	for _, post := range posts {
		results = append(results, r.post(psqlcore.SelectPostRow(post)))
	}

	return results
}