"use client";

import { useEffect, useMemo, useRef, useState } from "react";
import { Autocomplete, Chip, CircularProgress, TextField } from "@mui/material";
import { useTranslation } from "react-i18next";
import { searchItemCodes, type ItemCodeSearchHit } from "./itemCodeSearchApi";
import { parseItemCodeTokens } from "./parseItemCodeTokens";

type Props = {
  label: string;
  value: string[];
  onChange: (codes: string[]) => void;
  /** Live text in the box, including text that has not been picked from the list. */
  onInputValueChange?: (value: string) => void;
  placeholder?: string;
  disabled?: boolean;
  minChars?: number;
};

const hitLabel = (hit: ItemCodeSearchHit) =>
  hit.name ? `${hit.code} ${hit.name}` : hit.code;

/** FP-MTMS Version Checklist | Functions Ref. No. 81 | v1.0.1 | 2026-09-28 */
const AsyncItemCodeAutocomplete: React.FC<Props> = ({
  label,
  value,
  onChange,
  onInputValueChange,
  placeholder,
  disabled = false,
  minChars = 2,
}) => {
  const { t } = useTranslation("report");
  const [inputValue, setInputValue] = useState("");
  const [suggestions, setSuggestions] = useState<ItemCodeSearchHit[]>([]);
  const [labelByCode, setLabelByCode] = useState<Record<string, string>>({});
  const [isSearching, setIsSearching] = useState(false);

  const trimmedInput = inputValue.trim();
  const needsMoreChars = trimmedInput.length > 0 && trimmedInput.length < minChars;

  useEffect(() => {
    if (trimmedInput.length < minChars) {
      setSuggestions([]);
      setIsSearching(false);
      return;
    }

    const controller = new AbortController();
    let cancelled = false;
    const timer = window.setTimeout(async () => {
      setIsSearching(true);
      try {
        const hits = await searchItemCodes(trimmedInput, controller.signal);
        if (cancelled) return;
        setSuggestions(hits);
        setLabelByCode((prev) => {
          const next = { ...prev };
          hits.forEach((hit) => {
            next[hit.code] = hitLabel(hit);
          });
          return next;
        });
      } catch (error) {
        if (cancelled) return;
        if (error instanceof DOMException && error.name === "AbortError") return;
        setSuggestions([]);
      } finally {
        if (!cancelled) setIsSearching(false);
      }
    }, 300);

    return () => {
      cancelled = true;
      window.clearTimeout(timer);
      controller.abort();
    };
  }, [trimmedInput, minChars]);

  const selectedCodes = useMemo(
    () => new Set(value.map((code) => code.toUpperCase())),
    [value],
  );

  const options = useMemo(() => {
    const seen = new Set<string>();
    const codes: string[] = [];
    suggestions.forEach((hit) => {
      const key = hit.code.toUpperCase();
      if (seen.has(key) || selectedCodes.has(key)) return;
      seen.add(key);
      codes.push(hit.code);
    });
    return codes;
  }, [suggestions, selectedCodes]);

  useEffect(() => {
    const trimmed = inputValue.trim();
    if (!trimmed) return;
    const hit = suggestions.find((item) => item.code.toUpperCase() === trimmed.toUpperCase());
    if (hit) onInputValueChange?.(hit.code);
  }, [suggestions, inputValue, onInputValueChange]);

  const inputValueRef = useRef(inputValue);
  inputValueRef.current = inputValue;
  const previousValueRef = useRef(value);
  useEffect(() => {
    const previous = previousValueRef.current;
    previousValueRef.current = value;
    const tokens = parseItemCodeTokens(inputValueRef.current);
    if (tokens.length === 0) return;
    const previousKeys = new Set(previous.map((code) => code.toUpperCase()));
    const nextKeys = new Set(value.map((code) => code.toUpperCase()));
    const justCommitted = tokens.every(
      (token) => nextKeys.has(token.toUpperCase()) && !previousKeys.has(token.toUpperCase()),
    );
    if (!justCommitted) return;
    setInputValue("");
    onInputValueChange?.("");
  }, [value, onInputValueChange]);

  const noOptionsText = needsMoreChars
    ? t("typeToSearchItemCode", { min: minChars })
    : isSearching
      ? t("searchingItemCodes")
      : trimmedInput.length < minChars
        ? t("typeToSearchItemCode", { min: minChars })
        : t("noItemCodeMatches");

  const hasSelection = value.length > 0;

  return (
    <Autocomplete
      multiple
      freeSolo
      filterSelectedOptions
      disabled={disabled}
      options={options}
      value={value}
      inputValue={inputValue}
      loading={isSearching}
      filterOptions={(opts) =>
        trimmedInput.length < minChars
          ? []
          : opts.filter((code) => !selectedCodes.has(code.toUpperCase()))
      }
      isOptionEqualToValue={(option, selected) =>
        option.toUpperCase() === selected.toUpperCase()
      }
      autoHighlight
      noOptionsText={noOptionsText}
      sx={{
        '& .MuiOutlinedInput-root.MuiAutocomplete-inputRoot': hasSelection
          ? {
              alignItems: 'flex-start',
              alignContent: 'flex-start',
              flexWrap: 'wrap',
              minHeight: 56,
              paddingTop: '32px !important',
              paddingBottom: '8px !important',
              paddingLeft: '14px !important',
            }
          : {
              alignItems: 'center',
              height: 56,
              minHeight: 56,
              maxHeight: 56,
              boxSizing: 'border-box',
              paddingTop: '16.5px !important',
              paddingBottom: '16.5px !important',
              paddingLeft: '14px !important',
            },
        '& .MuiOutlinedInput-root.MuiAutocomplete-inputRoot .MuiAutocomplete-input': {
          fontSize: '1rem',
          padding: '0 !important',
        },
        '& .MuiOutlinedInput-root.MuiAutocomplete-inputRoot .MuiAutocomplete-input::placeholder': {
          color: 'text.disabled',
          opacity: 1,
        },
        '& .MuiAutocomplete-tag': {
          flex: '1 0 100%',
          maxWidth: '100%',
          width: '100%',
          margin: '6px 0 4px',
        },
      }}
      componentsProps={{
        popper: {
          placement: "top-start",
          modifiers: [{ name: "flip", enabled: false }],
        },
      }}
      onInputChange={(_, next, reason) => {
        if (reason === "reset") {
          setInputValue("");
          onInputValueChange?.("");
          return;
        }
        setInputValue(next);
        const trimmed = next.trim();
        const hit = suggestions.find((item) => item.code.toUpperCase() === trimmed.toUpperCase());
        onInputValueChange?.(hit?.code ?? next);
      }}
      onChange={(_, newValue) => {
        const codes = (Array.isArray(newValue) ? newValue : [])
          .map((item) => (typeof item === "string" ? item.trim() : String(item).trim()))
          .filter(Boolean);
        onChange(Array.from(new Set(codes)));
        setInputValue("");
      }}
      getOptionLabel={(option) => labelByCode[option] || option}
      renderTags={(selected, getTagProps) =>
        selected.map((option, index) => (
          <Chip
            variant="outlined"
            label={labelByCode[option] || option}
            {...getTagProps({ index })}
            key={`${option}-${index}`}
            sx={{
              height: 'auto',
              mt: index === 0 ? 0.5 : 0,
              py: 0.5,
              justifyContent: 'space-between',
              '& .MuiChip-label': {
                fontSize: '1rem',
                whiteSpace: 'normal',
                textAlign: 'left',
                lineHeight: 1.4,
                display: 'block',
              },
            }}
          />
        ))
      }
      renderInput={(params) => (
        <TextField
          {...params}
          fullWidth
          label={label}
          placeholder={hasSelection ? "" : (placeholder || "e.g. DEMO-FG-01")}
          helperText={t("typeToSearchItemCode", { min: minChars })}
          InputLabelProps={params.InputLabelProps}
          InputProps={{
            ...params.InputProps,
            endAdornment: (
              <>
                {isSearching ? <CircularProgress color="inherit" size={18} /> : null}
                {params.InputProps.endAdornment}
              </>
            ),
          }}
        />
      )}
    />
  );
};

export default AsyncItemCodeAutocomplete;