#include "bej_dictionary.h"
#include "bej_encoder_core.h"
#include "bej_tree.h"

#include "nlohmann/json.hpp"

#include <fstream>
#include <iostream>
#include <optional>
#include <span>

namespace libbej
{

// Buffer size for storing a single binary file data.
constexpr uint32_t maxBufferSize = 16 * 1024;

struct BejTestInputFiles
{
    const char* jsonFile;
    const char* schemaDictionaryFile;
    const char* annotationDictionaryFile;
    const char* errorDictionaryFile;
    const char* encodedStreamFile;
};

struct BejTestInputs
{
    nlohmann::json expectedJson;
    const uint8_t* schemaDictionary;
    const uint8_t* annotationDictionary;
    const uint8_t* errorDictionary;
    std::span<const uint8_t> encodedStream;
};

std::streamsize readBinaryFile(const char* fileName, std::span<uint8_t> buffer)
{
    std::ifstream inputStream(fileName, std::ios::binary);
    if (!inputStream.is_open())
    {
        std::cerr << "Cannot open file: " << fileName << "\n";
        return 0;
    }
    auto readLength = inputStream.readsome(
        reinterpret_cast<char*>(buffer.data()), buffer.size_bytes());
    if (inputStream.peek() != EOF)
    {
        std::cerr << "Failed to read the complete file: " << fileName
                  << "  read length: " << readLength << "\n";
        return 0;
    }
    return readLength;
}

std::optional<BejTestInputs> loadInputs(const BejTestInputFiles& files,
                                        bool readErrorDictionary = false)
{
    std::ifstream jsonInput(files.jsonFile);
    if (!jsonInput.is_open())
    {
        std::cerr << "Cannot open file: " << files.jsonFile << "\n";
        return std::nullopt;
    }
    nlohmann::json expJson;
    jsonInput >> expJson;

    static uint8_t schemaDictBuffer[maxBufferSize];
    if (readBinaryFile(files.schemaDictionaryFile,
                       std::span(schemaDictBuffer, maxBufferSize)) == 0)
    {
        return std::nullopt;
    }

    static uint8_t annoDictBuffer[maxBufferSize];
    if (readBinaryFile(files.annotationDictionaryFile,
                       std::span(annoDictBuffer, maxBufferSize)) == 0)
    {
        return std::nullopt;
    }

    static uint8_t encBuffer[maxBufferSize];
    auto encLen = readBinaryFile(files.encodedStreamFile,
                                 std::span(encBuffer, maxBufferSize));
    if (encLen == 0)
    {
        return std::nullopt;
    }

    static uint8_t errorDict[maxBufferSize];
    if (readErrorDictionary)
    {
        if (readBinaryFile(files.errorDictionaryFile,
                           std::span(errorDict, maxBufferSize)) == 0)
        {
            return std::nullopt;
        }
    }

    BejTestInputs inputs = {
        .expectedJson = expJson,
        .schemaDictionary = schemaDictBuffer,
        .annotationDictionary = annoDictBuffer,
        .errorDictionary = errorDict,
        .encodedStream = std::span(encBuffer, encLen),
    };
    return inputs;
}

} // namespace libbej