package postgres

import (
	"context"
	"encoding/json"
	"fmt"

	"git.nianxx.cn/wangxuming/NianAIGC/backend/internal/layercompositions"
)

const FindLayerCompositionSQL = `SELECT job_id, owner_id, base_asset_id, base_visible, layers, version, created_at, updated_at
FROM public.seedream_layer_compositions
WHERE owner_id = $1::text AND job_id = $2::text
LIMIT 1`

const SaveLayerCompositionSQL = `WITH updated AS (
  UPDATE public.seedream_layer_compositions SET
  base_asset_id = $3::text,
  base_visible = $4::boolean,
  layers = $5::jsonb,
  version = seedream_layer_compositions.version + 1,
  updated_at = now()
  WHERE job_id = $1::text
    AND owner_id = $2::text
    AND version = $6::bigint
    AND $6::bigint > 0
  RETURNING job_id, owner_id, base_asset_id, base_visible, layers, version, created_at, updated_at
), inserted AS (
  INSERT INTO public.seedream_layer_compositions (
    job_id, owner_id, base_asset_id, base_visible, layers, version, created_at, updated_at
  )
  SELECT $1::text, $2::text, $3::text, $4::boolean, $5::jsonb, 1, now(), now()
  WHERE $6::bigint = 0
  ON CONFLICT (job_id) DO NOTHING
  RETURNING job_id, owner_id, base_asset_id, base_visible, layers, version, created_at, updated_at
)
SELECT job_id, owner_id, base_asset_id, base_visible, layers, version, created_at, updated_at FROM updated
UNION ALL
SELECT job_id, owner_id, base_asset_id, base_visible, layers, version, created_at, updated_at FROM inserted
LIMIT 1`

func (db *Database) FindLayerComposition(ctx context.Context, ownerID, jobID string) (layercompositions.Composition, bool, error) {
	if err := db.available(); err != nil {
		return layercompositions.Composition{}, false, err
	}
	rows, err := db.querier.Query(ctx, FindLayerCompositionSQL, ownerID, jobID)
	if err != nil {
		return layercompositions.Composition{}, false, fmt.Errorf("find layer composition: %w", err)
	}
	defer rows.Close()
	if !rows.Next() {
		if err := rows.Err(); err != nil {
			return layercompositions.Composition{}, false, fmt.Errorf("read layer composition: %w", err)
		}
		return layercompositions.Composition{}, false, nil
	}
	composition, err := scanLayerComposition(rows)
	if err != nil {
		return layercompositions.Composition{}, false, err
	}
	return composition, true, rows.Err()
}

func (db *Database) SaveLayerComposition(ctx context.Context, composition layercompositions.Composition, expectedVersion int64) (layercompositions.Composition, error) {
	if err := db.available(); err != nil {
		return layercompositions.Composition{}, err
	}
	layers, err := json.Marshal(composition.Layers)
	if err != nil {
		return layercompositions.Composition{}, fmt.Errorf("encode layer composition: %w", err)
	}
	rows, err := db.querier.Query(ctx, SaveLayerCompositionSQL,
		composition.JobID, composition.OwnerID, composition.BaseAssetID,
		composition.BaseVisible, layers, expectedVersion,
	)
	if err != nil {
		return layercompositions.Composition{}, fmt.Errorf("save layer composition: %w", err)
	}
	defer rows.Close()
	if !rows.Next() {
		if err := rows.Err(); err != nil {
			return layercompositions.Composition{}, fmt.Errorf("read saved layer composition: %w", err)
		}
		return layercompositions.Composition{}, layercompositions.ErrConflict
	}
	saved, err := scanLayerComposition(rows)
	if err != nil {
		return layercompositions.Composition{}, err
	}
	return saved, rows.Err()
}

func scanLayerComposition(rows Rows) (layercompositions.Composition, error) {
	var composition layercompositions.Composition
	var rawLayers []byte
	if err := rows.Scan(
		&composition.JobID, &composition.OwnerID, &composition.BaseAssetID,
		&composition.BaseVisible, &rawLayers, &composition.Version,
		&composition.CreatedAt, &composition.UpdatedAt,
	); err != nil {
		return layercompositions.Composition{}, fmt.Errorf("scan layer composition: %w", err)
	}
	if err := json.Unmarshal(rawLayers, &composition.Layers); err != nil {
		return layercompositions.Composition{}, fmt.Errorf("decode layer composition: %w", err)
	}
	if composition.Layers == nil {
		composition.Layers = []layercompositions.Layer{}
	}
	return composition, nil
}