#include "BookCheck.h"

// Mostly borrowed from Fix Note icon for SkyUI by 0xC0000005
namespace BookCheck
{
	std::vector<RE::TESObjectBOOK*> validBooks;

	void PreloadBookList()
	{
		const auto dataHandler = RE::TESDataHandler::GetSingleton();

		if (!dataHandler) {
			return;
		}
		
		RE::BGSKeyword* recipeKeyword = dataHandler->LookupForm<RE::BGSKeyword>(0xF5CB0, "Skyrim.esm"); // VendorItemRecipe

		for (const auto& form : dataHandler->GetFormArray<RE::TESObjectBOOK>()) {
			if (!form || form->TeachesSpell()) {
				continue;
			}
			if (form->HasKeyword(recipeKeyword) || IsBook(form)) {
				validBooks.push_back(form);
			}
		}
	}
	
	std::vector<RE::TESObjectBOOK*> GetBookList()
	{
		return validBooks;
	}

	const char* ExtractFileName(const char* const path, size_t& fileNameLength)
	{
		if (!path) {
			fileNameLength = 0;
			return NULL;
		}

		const char* ptr = path;
		const char* fileNameStart = NULL;

		while (*ptr != 0) {
			char value = *ptr;

			if (value == '\\' || value == '/') {
				fileNameStart = ptr + 1;
			}

			ptr++;
		}

		const char* result = fileNameStart ? fileNameStart : path;

		fileNameLength = ptr - result;

		return result;
	}

	// Performs a case-sensitive search for 'needle' in the specified string,
	// excluding any matches that are part of a larger word.
	bool ContainsWholeWord(const char* const haystack, const size_t haystackLength,
		const char* const needle, const size_t needleLength)
	{
		if (haystackLength >= needleLength) {
			for (size_t i = 0; i < haystackLength; i++) {
				if (haystack[i] != needle[0]) {
					continue;
				}

				size_t j = i + 1;
				size_t k = 1;

				while (j < haystackLength && k < needleLength && haystack[j] == needle[k]) {
					j++;
					k++;
				}

				if (k == needleLength) {
					// Check that the match is not part of a larger word.

					char next = haystack[j];

					return !(next >= 'a' && next <= 'z');
				}
			}
		}

		return false;
	}

	bool StartsWith(const char* haystack, size_t haystackLength,
		const char* needle, size_t needleLength)
	{
		return haystackLength >= needleLength && memcmp(haystack, needle, needleLength) == 0;
	}

	bool IsNote(const char* const modelFileName, size_t modelFileNameLength)
	{
		// Most items will use one of the note models from the base game, e.g. Note01.nif.
		if (ContainsWholeWord(modelFileName, modelFileNameLength, "Note", 4)) {
			return true;
		}

		// The Creation Club Fishing mod does not include 'Note' the inventory art model names for the
		// regional fishing maps, instead those items use the following format: FishMap<region>.
		if (StartsWith(modelFileName, modelFileNameLength, "FishMap", 7)) {
			return true;
		}

		return false;
	}

	bool IsJournal(const char* const modelFileName, size_t modelFileNameLength)
	{
		return ContainsWholeWord(modelFileName, modelFileNameLength, "Journal", 7);
	}

	bool IsBook(RE::TESObjectBOOK* book)
	{
		if (!book || !book->inventoryModel) {
			return false;
		}

		RE::BGSSoundDescriptorForm* pickupSound = book->As<RE::BGSPickupPutdownSounds>()->pickupSound;

		if (pickupSound && pickupSound->formID == 0xC7A54) { // ITMNoteUp
			return false;
		}

		size_t modelFileNameLength;
		const char* const modelFileName = BookCheck::ExtractFileName(book->inventoryModel->GetModel(), modelFileNameLength);

		if (modelFileNameLength == 0) {
			return false;
		}

		if (IsNote(modelFileName, modelFileNameLength) || IsJournal(modelFileName, modelFileNameLength)) {
			return false;
		}

		return true;
	}
}