package controllers

import (
	"encoding/json"
	"fmt"

	"nearle/models"

	"github.com/gofiber/fiber/v2"
)

// parseStockRequests reads either one request or a list of them.
//
// Sniffing the first byte rather than trying one shape and falling back to the
// other: BodyParser consumes what it reads, so a failed first attempt can leave
// nothing for the second. The body is JSON here and `[` is unambiguous.
func parseStockRequests(c *fiber.Ctx) ([]models.StockRequest, error) {
	body := c.Body()

	for _, b := range body {
		switch b {
		case ' ', '\t', '\r', '\n':
			continue
		case '[':
			var many []models.StockRequest
			if err := json.Unmarshal(body, &many); err != nil {
				return nil, err
			}
			return many, nil
		}
		break
	}

	var one models.StockRequest
	if err := c.BodyParser(&one); err != nil {
		return nil, err
	}
	return []models.StockRequest{one}, nil
}

// dedupeIDs drops repeats and anything non-positive, preserving order.
//
// Repeats matter here rather than being tidiness: approving adds stock, so the
// same id twice in one batch would try to receive the same delivery twice. The
// service has its own guard, but a batch should not be relying on it.
func dedupeIDs(ids []int) []int {
	seen := make(map[int]bool, len(ids))
	out := make([]int, 0, len(ids))
	for _, id := range ids {
		if id <= 0 || seen[id] {
			continue
		}
		seen[id] = true
		out = append(out, id)
	}
	return out
}

// stockBatchMessage says what happened in words a merchant can act on.
//
// "8 approved, 2 could not be" beats "Success" when two of ten did not land —
// the whole point of reporting per row is that the person can go and look.
func stockBatchMessage(ok, failed int, verb string) string {
	if failed == 0 {
		return fmt.Sprintf("%d %s", ok, verb)
	}
	return fmt.Sprintf("%d %s, %d could not be", ok, verb, failed)
}