// backend\device_lookups.go

package main

import (
	"context"
	"fmt"
	"net/http"
	"strings"

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

type DeviceLookupOption struct {
	ID   string `json:"id"`
	Name string `json:"name"`
}

type CreateDeviceLookupRequest struct {
	Name string `json:"name"`
}

func (s *Server) handleDeviceLookups(w http.ResponseWriter, r *http.Request) {
	manufacturers, err := listDeviceLookupOptions(r.Context(), s.db, "device_manufacturers")
	if err != nil {
		writeError(w, http.StatusInternalServerError, "Hersteller konnten nicht geladen werden")
		return
	}

	locations, err := listDeviceLookupOptions(r.Context(), s.db, "device_locations")
	if err != nil {
		writeError(w, http.StatusInternalServerError, "Standorte konnten nicht geladen werden")
		return
	}

	writeJSON(w, http.StatusOK, map[string]any{
		"manufacturers": manufacturers,
		"locations":     locations,
	})
}

func (s *Server) handleCreateDeviceManufacturer(w http.ResponseWriter, r *http.Request) {
	s.handleCreateDeviceLookup(w, r, "device_manufacturers", "Hersteller")
}

func (s *Server) handleDeleteDeviceManufacturer(w http.ResponseWriter, r *http.Request) {
	s.handleDeleteDeviceLookup(w, r, "device_manufacturers", "Hersteller")
}

func (s *Server) handleCreateDeviceLocation(w http.ResponseWriter, r *http.Request) {
	s.handleCreateDeviceLookup(w, r, "device_locations", "Standort")
}

func (s *Server) handleCreateDeviceLookup(
	w http.ResponseWriter,
	r *http.Request,
	tableName string,
	label string,
) {
	var input CreateDeviceLookupRequest

	if err := readJSON(r, &input); err != nil {
		writeError(w, http.StatusBadRequest, "Invalid JSON")
		return
	}

	name := strings.TrimSpace(input.Name)
	if name == "" {
		writeError(w, http.StatusBadRequest, label+" ist erforderlich")
		return
	}

	option, err := upsertDeviceLookupOption(r.Context(), s.db, tableName, name)
	if err != nil {
		writeError(w, http.StatusInternalServerError, label+" konnte nicht gespeichert werden")
		return
	}

	writeJSON(w, http.StatusCreated, map[string]any{
		"option": option,
	})
}

func (s *Server) handleDeleteDeviceLookup(
	w http.ResponseWriter,
	r *http.Request,
	tableName string,
	label string,
) {
	id := strings.TrimSpace(r.PathValue("id"))
	if id == "" {
		writeError(w, http.StatusBadRequest, label+" ist erforderlich")
		return
	}

	commandTag, err := s.db.Exec(
		r.Context(),
		fmt.Sprintf(`DELETE FROM %s WHERE id = $1`, tableName),
		id,
	)
	if err != nil {
		writeError(w, http.StatusInternalServerError, label+" konnte nicht gelöscht werden")
		return
	}

	if commandTag.RowsAffected() == 0 {
		writeError(w, http.StatusNotFound, label+" wurde nicht gefunden")
		return
	}

	writeJSON(w, http.StatusOK, map[string]any{
		"deleted": true,
	})
}

func listDeviceLookupOptions(
	ctx context.Context,
	db interface {
		Query(ctx context.Context, sql string, args ...any) (pgx.Rows, error)
	},
	tableName string,
) ([]DeviceLookupOption, error) {
	query := fmt.Sprintf(
		`
		SELECT id::TEXT, name
		FROM %s
		ORDER BY lower(name) ASC
		`,
		tableName,
	)

	rows, err := db.Query(ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	options := []DeviceLookupOption{}

	for rows.Next() {
		var option DeviceLookupOption

		if err := rows.Scan(&option.ID, &option.Name); err != nil {
			return nil, err
		}

		options = append(options, option)
	}

	if err := rows.Err(); err != nil {
		return nil, err
	}

	return options, nil
}

func ensureDeviceLookupValues(
	ctx context.Context,
	tx pgx.Tx,
	manufacturer string,
	location string,
) error {
	if err := ensureOptionalDeviceLookupValue(ctx, tx, "device_manufacturers", manufacturer); err != nil {
		return err
	}

	if err := ensureOptionalDeviceLookupValue(ctx, tx, "device_locations", location); err != nil {
		return err
	}

	return nil
}

func ensureOptionalDeviceLookupValue(
	ctx context.Context,
	db deviceTransaction,
	tableName string,
	name string,
) error {
	name = strings.TrimSpace(name)
	if name == "" {
		return nil
	}

	_, err := upsertDeviceLookupOption(ctx, db, tableName, name)
	return err
}

func upsertDeviceLookupOption(
	ctx context.Context,
	db deviceTransaction,
	tableName string,
	name string,
) (DeviceLookupOption, error) {
	name = strings.TrimSpace(name)
	normalizedName := strings.ToLower(name)

	query := fmt.Sprintf(
		`
		INSERT INTO %s (
			name,
			normalized_name
		)
		VALUES ($1, $2)
		ON CONFLICT (normalized_name)
		DO UPDATE SET
			updated_at = now()
		RETURNING id::TEXT, name
		`,
		tableName,
	)

	var option DeviceLookupOption

	err := db.QueryRow(
		ctx,
		query,
		name,
		normalizedName,
	).Scan(&option.ID, &option.Name)

	return option, err
}