#include <cstdint>
#include <cstring>
#include <span>
#include <vector>
#include <map>
#include <string>
#include <zng_compat.hpp>
#include <exception>

namespace steam2ng{ 
    namespace valve_types {
        #pragma pack(push, 1)
        using u32 = uint32_t;
        using AppId_t = u32;
        using AppVersionId_t = u32;
        using FileId_t = u32;
        using ManifestNode_t = u32;
        struct TMstBinHeader // sizeof=0x38
        {                                       // XREF: _ZN4Grid12CManifestBinC2EP8_IO_FILEl/r
                                                // _ZN4Grid12CManifestBinC1EP8_IO_FILEl/r ...
            u32 u32MstVersion;                  // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long):loc_FA270/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+187/r ...
            AppId_t uAppId;                     // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+18C/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+18C/r
            AppVersionId_t uVerId;              // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+192/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+192/r
            u32 u32NumOfNodes;                  // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+198/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long):loc_FA418/r ...
            u32 u32NumOfFiles;                  // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+19E/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+19E/r
            u32 u32CompressionBlkSize;          // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1A4/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1A4/r
            u32 u32BinarySize;                  // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long):loc_FA2E8/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1AA/r ...
            u32 u32StringTableSize;             // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1B0/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1B0/r
            u32 u32HashBuckets;                 // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1B6/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1B6/r
            u32 u32NumMfpNodes;                 // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1BC/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1BC/r
            u32 u32NumUserConfigNodes;          // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1C2/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1C2/r
            u32 u32DepotInfo;                   // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1C8/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1C8/r
            u32 u32FingerPrint;                 // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1CE/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1CE/r
            u32 u32Checksum;                    // XREF: Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1D4/r
                                                // Grid::CManifestBin::CManifestBin(_IO_FILE *,long)+1D4/r
        };

        struct TDirNodeBin // sizeof=0x1C
        {                                       // XREF: Grid::CManifestBin::TDirNode.dirNodeBin/r
            u32 u32NameOffset;
            u32 u32CountOrSize;
            FileId_t uFileId;
            u32 u32Flags;
            ManifestNode_t u32Parent;
            ManifestNode_t u32NextSibling;
            ManifestNode_t u32FirstChild;
        };
        #pragma pack(pop)
    }
    struct manifest{
        static inline manifest from_memory(std::span<std::byte> chars) {
            auto header = *reinterpret_cast<valve_types::TMstBinHeader*>(chars.data());

            if (!(header.u32MstVersion == 4 || header.u32MstVersion == 3)) {
                throw std::runtime_error("manifest::from_memory: version isn't 3 or 4");
            }
            if (header.u32BinarySize != chars.size()) {
                throw std::runtime_error("manifest::from_memory: manifest size is wrong");
            }

            auto temp_chksum = header.u32Checksum;
            auto ptr_hdr = reinterpret_cast<valve_types::TMstBinHeader*>(chars.data());
            ptr_hdr->u32Checksum = 0;
            ptr_hdr->u32FingerPrint = 0;
            auto chk = zng_adler32(0, reinterpret_cast<uint8_t*>(chars.data()), chars.size());
            if (temp_chksum != chk) {
                throw std::runtime_error("manifest::from_memory: checksum is wrong");
            }

            valve_types::TDirNodeBin* first = reinterpret_cast<valve_types::TDirNodeBin*>(chars.data() + sizeof(valve_types::TMstBinHeader));

            std::vector<valve_types::TDirNodeBin> bins;
            std::map<valve_types::FileId_t, std::string> tofull;

            bins.resize(header.u32NumOfNodes);
            memcpy(bins.data(), first, sizeof(valve_types::TDirNodeBin)*header.u32NumOfNodes);
            
            const char* string_table =  reinterpret_cast<const char*>(chars.data() + sizeof(valve_types::TMstBinHeader) + (sizeof(valve_types::TDirNodeBin)*header.u32NumOfNodes));

            for (auto entry : bins) {
                std::string path;
                auto currnet_entry = &entry;
                while (currnet_entry->u32Parent != 0xffffffff) {
                    path.insert(0, string_table + currnet_entry->u32NameOffset);
                    if (currnet_entry->u32Parent != 0) {
                        path.insert(0, "/");
                    }
                    currnet_entry = &bins[currnet_entry->u32Parent];            
                }
                tofull[entry.uFileId] = path;
            }
            return {header,bins,tofull};
        }
        valve_types::TMstBinHeader hdr;
        std::vector<valve_types::TDirNodeBin> directory_nodes;
        std::map<valve_types::FileId_t, std::string> id_to_full;
    };

    enum class compression_type : uint32_t {
        uncompressed = 0,
        compressed,
        compressed_and_encrypted,
        encrypted
    };    
}