// Copyright (c) 2026 Storm Dragon
// SPDX-License-Identifier: GPL-3.0-or-later

// Package spellcheck owns offline dictionary work and personal exceptions.
package spellcheck

/*
#cgo LDFLAGS: -ldl
#include "native.h"
#include <stdlib.h>
*/
import "C"

import (
	"fmt"
	"unsafe"
)

// Dictionary is used only by the service's worker, including Close.
type Dictionary interface {
	Check(string) (bool, error)
	Suggest(string) ([]string, error)
	Close()
}

type EnchantDictionary struct {
	native *C.SpellDictionary
}

func open_dictionary(language string) (Dictionary, error) {
	if language == "" {
		return nil, fmt.Errorf("the session has no spelling language")
	}
	tag := C.CString(language)
	defer C.free(unsafe.Pointer(tag))
	var status C.int
	native := C.spell_dictionary_open(tag, &status)
	if native == nil {
		switch status {
		case 1:
			return nil, fmt.Errorf("Enchant 2 could not be loaded")
		case 2:
			return nil, fmt.Errorf("Enchant 2 has an incompatible interface")
		case 4:
			return nil, fmt.Errorf("dictionary for %s is unavailable", language)
		default:
			return nil, fmt.Errorf("could not initialize Enchant")
		}
	}
	return &EnchantDictionary{native: native}, nil
}

func (d *EnchantDictionary) Check(word string) (bool, error) {
	value := C.CString(word)
	defer C.free(unsafe.Pointer(value))
	result := C.spell_dictionary_check(d.native, value, C.size_t(len(word)))
	if result < 0 {
		return false, fmt.Errorf("dictionary check failed")
	}
	return result == 0, nil
}

func (d *EnchantDictionary) Suggest(word string) ([]string, error) {
	value := C.CString(word)
	defer C.free(unsafe.Pointer(value))
	var count C.size_t
	list := C.spell_dictionary_suggest(d.native, value, C.size_t(len(word)), &count)
	if list == nil {
		return nil, nil
	}
	defer C.spell_dictionary_free_suggestions(d.native, list)
	// Preserve provider ranking, with a bounded result set for the picker.
	var suggestions []string
	seen := make(map[string]bool)
	for _, item := range unsafe.Slice(list, int(min(count, 128))) {
		word := C.GoString(item)
		if word != "" && !seen[word] {
			seen[word] = true
			suggestions = append(suggestions, word)
		}
	}
	return suggestions, nil
}

func (d *EnchantDictionary) Close() {
	C.spell_dictionary_close(d.native)
}