package postgres

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"time"

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

const templateColumns = `id, owner_id, name, description, prompt, preview_image_url, settings, sort_order, created_at, updated_at`

const ListImageTemplatesSQL = `SELECT ` + templateColumns + ` FROM public.image_templates WHERE owner_id = $1::text ORDER BY sort_order ASC, updated_at DESC`
const CreateImageTemplateSQL = `INSERT INTO public.image_templates (id, owner_id, name, description, prompt, preview_image_url, settings, sort_order, created_at, updated_at) VALUES ($1::text,$2::text,$3::text,$4::text,$5::text,$6::text,$7::jsonb,$8::integer,$9::timestamptz,$10::timestamptz) RETURNING ` + templateColumns
const UpdateImageTemplateSQL = `UPDATE public.image_templates SET name=COALESCE($3::text,name), description=CASE WHEN $4::boolean THEN $5::text ELSE description END, prompt=COALESCE($6::text,prompt), preview_image_url=CASE WHEN $7::boolean THEN $8::text ELSE preview_image_url END, settings=COALESCE($9::jsonb,settings), sort_order=COALESCE($10::integer,sort_order), updated_at=$11::timestamptz WHERE owner_id=$1::text AND id=$2::text RETURNING ` + templateColumns
const DeleteImageTemplateSQL = `DELETE FROM public.image_templates WHERE owner_id=$1::text AND id=$2::text RETURNING ` + templateColumns

func (db *Database) ListTemplates(ctx context.Context, owner string) ([]templates.Template, error) {
	if err := db.available(); err != nil {
		return nil, err
	}
	rows, err := db.querier.Query(ctx, ListImageTemplatesSQL, owner)
	if err != nil {
		return nil, fmt.Errorf("list image templates: %w", err)
	}
	defer rows.Close()
	items := []templates.Template{}
	for rows.Next() {
		item, current := scanTemplate(rows)
		if current != nil {
			return nil, current
		}
		items = append(items, item)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("read image templates: %w", err)
	}
	return items, nil
}

func (db *Database) CreateTemplate(ctx context.Context, item templates.Template) (templates.Template, error) {
	settings, err := json.Marshal(item.Settings)
	if err != nil {
		return templates.Template{}, fmt.Errorf("encode template settings: %w", err)
	}
	return db.requiredTemplate(ctx, CreateImageTemplateSQL, item.ID, item.OwnerID, item.Name, nullableText(item.Description), item.Prompt, nullableText(item.PreviewImageURL), settings, item.SortOrder, item.CreatedAt, item.UpdatedAt)
}

func (db *Database) UpdateTemplate(ctx context.Context, owner, id string, patch templates.Patch, now time.Time) (templates.Template, bool, error) {
	var settings any
	if patch.Settings != nil {
		encoded, err := json.Marshal(*patch.Settings)
		if err != nil {
			return templates.Template{}, false, fmt.Errorf("encode template settings: %w", err)
		}
		settings = encoded
	}
	args := []any{owner, id, patch.Name, patch.Description != nil, pointerText(patch.Description), patch.Prompt, patch.PreviewImageURL != nil, pointerText(patch.PreviewImageURL), settings, patch.SortOrder, now}
	return db.oneTemplate(ctx, UpdateImageTemplateSQL, args...)
}

func (db *Database) DeleteTemplate(ctx context.Context, owner, id string) (templates.Template, bool, error) {
	return db.oneTemplate(ctx, DeleteImageTemplateSQL, owner, id)
}

func (db *Database) requiredTemplate(ctx context.Context, query string, args ...any) (templates.Template, error) {
	item, found, err := db.oneTemplate(ctx, query, args...)
	if err != nil {
		return templates.Template{}, err
	}
	if !found {
		return templates.Template{}, fmt.Errorf("image template write returned no row")
	}
	return item, nil
}
func (db *Database) oneTemplate(ctx context.Context, query string, args ...any) (templates.Template, bool, error) {
	if err := db.available(); err != nil {
		return templates.Template{}, false, err
	}
	rows, err := db.querier.Query(ctx, query, args...)
	if err != nil {
		return templates.Template{}, false, fmt.Errorf("query image template: %w", err)
	}
	defer rows.Close()
	if !rows.Next() {
		if err := rows.Err(); err != nil {
			return templates.Template{}, false, fmt.Errorf("read image template: %w", err)
		}
		return templates.Template{}, false, nil
	}
	item, err := scanTemplate(rows)
	if err != nil {
		return templates.Template{}, false, err
	}
	if err := rows.Err(); err != nil {
		return templates.Template{}, false, fmt.Errorf("read image template: %w", err)
	}
	return item, true, nil
}
func scanTemplate(rows Rows) (templates.Template, error) {
	var item templates.Template
	var description, preview sql.NullString
	var settings []byte
	if err := rows.Scan(&item.ID, &item.OwnerID, &item.Name, &description, &item.Prompt, &preview, &settings, &item.SortOrder, &item.CreatedAt, &item.UpdatedAt); err != nil {
		return templates.Template{}, fmt.Errorf("scan image template: %w", err)
	}
	if description.Valid {
		item.Description = description.String
	}
	if preview.Valid {
		item.PreviewImageURL = preview.String
	}
	if len(settings) == 0 {
		settings = []byte(`{}`)
	}
	if err := json.Unmarshal(settings, &item.Settings); err != nil {
		return templates.Template{}, fmt.Errorf("decode template settings: %w", err)
	}
	return item, nil
}
func nullableText(value string) any {
	if value == "" {
		return nil
	}
	return value
}
func pointerText(value *string) any {
	if value == nil || *value == "" {
		return nil
	}
	return *value
}

var _ templates.Catalog = (*Database)(nil)