import { useState } from "react";
import { Alert, View } from "react-native";
import { router } from "expo-router";
import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
import { api } from "@/lib/api";
import { t } from "@/lib/i18n";
import { Body, Button, Card, Heading, Input, Row, Screen, Small, Spacer } from "@/components/ui";

/**
 * Måltidsloggning (spec §23): tidigare måltid, favoritrecept eller manuellt.
 * Tallriksfoto loggas via Skanna-fliken. Näringsvärden hittas ALDRIG på:
 * manuell loggning kräver egna värden eller känt recept/livsmedel.
 */

/** Etiketter ur i18n-katalogen (myday.mealType.<typ>) – id:na är stabila API-värden. */
const MEAL_TYPES = ["breakfast", "lunch", "dinner", "snack"] as const;

interface RecentMeal {
  id: string;
  titleSv: string;
  mealType: string;
  nutrition: {
    kcal: number;
    proteinG: number;
    carbsG: number;
    fatG: number;
    saturatedFatG: number;
    fiberG: number;
    sugarG: number;
    saltG: number;
  };
}

export default function LogMealScreen() {
  const queryClient = useQueryClient();
  const [mealType, setMealType] = useState<string>("lunch");
  const [title, setTitle] = useState("");
  const [kcal, setKcal] = useState("");
  const [protein, setProtein] = useState("");

  const recent = useQuery({
    queryKey: ["recent-meals"],
    queryFn: () => api<{ meals: RecentMeal[] }>("/v1/meals/recent"),
  });

  const log = useMutation({
    mutationFn: (body: unknown) => api("/v1/meals", { method: "POST", body }),
    onSuccess: async () => {
      await queryClient.invalidateQueries({ queryKey: ["day"] });
      router.back();
    },
    onError: (err) =>
      Alert.alert(t("common.oops"), err instanceof Error ? err.message : t("common.error")),
  });

  const today = new Date().toISOString().slice(0, 10);

  const logManual = () => {
    if (!title.trim() || !kcal) {
      Alert.alert(t("logmeal.validationTitle"), t("logmeal.validationBody"));
      return;
    }
    log.mutate({
      date: today,
      mealType,
      source: "manual",
      titleSv: title.trim(),
      nutritionOverride: {
        kcal: Number(kcal),
        proteinG: Number(protein) || 0,
        carbsG: 0,
        fatG: 0,
        saturatedFatG: 0,
        fiberG: 0,
        sugarG: 0,
        saltG: 0,
      },
    });
  };

  const logPrevious = (meal: RecentMeal) => {
    log.mutate({
      date: today,
      mealType,
      source: "previous_meal",
      titleSv: meal.titleSv,
      nutritionOverride: meal.nutrition,
    });
  };

  return (
    <Screen>
      <Heading>{t("logmeal.mealTypeTitle")}</Heading>
      <Row>
        {MEAL_TYPES.map((id) => (
          <Button
            key={id}
            label={t(`myday.mealType.${id}`)}
            variant={mealType === id ? "secondary" : "ghost"}
            onPress={() => setMealType(id)}
          />
        ))}
      </Row>

      <Spacer />
      <Heading>{t("logmeal.quickTitle")}</Heading>
      <Small>{t("logmeal.quickSubtitle")}</Small>
      {(recent.data?.meals ?? []).slice(0, 5).map((meal) => (
        <Card key={meal.id} onPress={() => logPrevious(meal)}>
          <Row style={{ justifyContent: "space-between" }}>
            <Body>{meal.titleSv}</Body>
            <Small>{Math.round(meal.nutrition.kcal)} kcal</Small>
          </Row>
        </Card>
      ))}

      <Spacer />
      <Heading>{t("logmeal.manualTitle")}</Heading>
      <Input placeholder={t("logmeal.whatPlaceholder")} value={title} onChangeText={setTitle} />
      <Row>
        <View style={{ flex: 1 }}>
          <Input placeholder="kcal" keyboardType="numeric" value={kcal} onChangeText={setKcal} />
        </View>
        <View style={{ flex: 1 }}>
          <Input
            placeholder={t("logmeal.proteinPlaceholder")}
            keyboardType="numeric"
            value={protein}
            onChangeText={setProtein}
          />
        </View>
      </Row>
      <Button label={t("myday.logMeal")} onPress={logManual} loading={log.isPending} />
      <Small>{t("logmeal.photoTip")}</Small>
    </Screen>
  );
}
