// tools/loading_tip_patcher/src/main.cpp
// EU4 1.37.5 loading-screen cycle-rate patcher.
//
// Repoints the two `movsd xmm1,[8.0]` instructions in sub_14081AF10
// (loading-screen timer setup) to a code cave holding the user's interval.
// Only the loading-screen timer is affected; 9 other 8.0 sites are untouched.
//
// Build (MinGW-w64 GCC):
//   x86_64-w64-mingw32-gcc -O2 -Wall -static -o bin/loading_tip_patcher.exe src/main.cpp -lbcrypt -lkernel32 -lpsapi
//
// Usage:
//   loading_tip_patcher.exe --apply    patch running eu4.exe
//   loading_tip_patcher.exe --revert   restore original bytes
//   loading_tip_patcher.exe --status   show state.json
//
// config.json (REQUIRED for --apply):  { "tip_interval_seconds": 30 }

#include <windows.h>
#include <bcrypt.h>
#include <psapi.h>
#include <tlhelp32.h>
#include <strsafe.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

// ---- Patch sites (preferred-base VMAs; ASLR-adjusted at runtime) ----
static const uint64_t PREFERRED_BASE  = 0x140000000ULL;
static const uint64_t CAVE_VMA        = 0x14081DE66ULL; // 10 bytes of 0xCC; use first 8
static const uint64_t SITE1_MOVSD_VMA = 0x14081D83AULL; // movsd xmm1,[8.0] (disp32 at +4)
static const uint64_t SITE2_MOVSD_VMA = 0x14081D943ULL; // movsd xmm1,[8.0] (disp32 at +4)
static const uint8_t  SITE1_ORIG[4]   = { 0x26, 0x3F, 0x5A, 0x01 };
static const uint8_t  SITE1_NEW[4]    = { 0x24, 0x06, 0x00, 0x00 };
static const uint8_t  SITE2_ORIG[4]   = { 0x1D, 0x3E, 0x5A, 0x01 };
static const uint8_t  SITE2_NEW[4]    = { 0x1B, 0x05, 0x00, 0x00 };

static const wchar_t* EU4_EXE_W = L"C:\\Program Files (x86)\\Steam\\steamapps\\common\\Europa Universalis IV\\eu4.exe";
static const char* EU4_EXE = "C:\\Program Files (x86)\\Steam\\steamapps\\common\\Europa Universalis IV\\eu4.exe";

// ---- helpers ----
static int json_get_double(const char* path, const char* key, double* out) {
    FILE* fp = fopen(path, "rb");
    if (!fp) return -1;
    fseek(fp, 0, SEEK_END); long sz = ftell(fp); fseek(fp, 0, SEEK_SET);
    char* buf = (char*)malloc(sz + 1); if (!buf) { fclose(fp); return -1; }
    fread(buf, 1, sz, fp); buf[sz] = '\0'; fclose(fp);
    char needle[64]; snprintf(needle, sizeof(needle), "\"%s\"", key);
    char* p = strstr(buf, needle);
    if (!p) { free(buf); return -2; }
    p = strchr(p, ':'); if (!p) { free(buf); return -2; }
    p++; while (*p==' '||*p=='\t'||*p=='\n'||*p=='\r') p++;
    *out = strtod(p, NULL); free(buf); return 0;
}

static int sha256_file(const wchar_t* path, uint8_t out[32]) {
    BCRYPT_ALG_HANDLE hAlg=NULL; BCRYPT_HASH_HANDLE hHash=NULL;
    PUCHAR hObj=NULL; HANDLE hF=INVALID_HANDLE_VALUE; int rc=-1;
    if (!BCRYPT_SUCCESS(BCryptOpenAlgorithmProvider(&hAlg,BCRYPT_SHA256_ALGORITHM,NULL,0)))return -1;
    DWORD sz=0,rs=0; BCryptGetProperty(hAlg,BCRYPT_OBJECT_LENGTH,(PUCHAR)&sz,sizeof(sz),&rs,0);
    hObj=(PUCHAR)HeapAlloc(GetProcessHeap(),0,sz); if(!hObj)goto d;
    if(!BCRYPT_SUCCESS(BCryptCreateHash(hAlg,&hHash,hObj,sz,NULL,0,0)))goto d;
    hF=CreateFileW(path,GENERIC_READ,FILE_SHARE_READ,NULL,OPEN_EXISTING,0,NULL);
    if(hF==INVALID_HANDLE_VALUE)goto d;
    {BYTE b[1<<16];DWORD n; while(ReadFile(hF,b,sizeof(b),&n,NULL)&&n>0)
        if(!BCRYPT_SUCCESS(BCryptHashData(hHash,b,n,0)))goto d;}
    if(!BCRYPT_SUCCESS(BCryptFinishHash(hHash,out,32,0)))goto d; rc=0;
d: if(hF!=INVALID_HANDLE_VALUE)CloseHandle(hF); if(hHash)BCryptDestroyHash(hHash);
   if(hObj)HeapFree(GetProcessHeap(),0,hObj); if(hAlg)BCryptCloseAlgorithmProvider(hAlg,0);
   return rc;
}
static void to_hex(const uint8_t h[32], char o[65]) {
    static const char*H="0123456789abcdef";
    for(int i=0;i<32;i++){o[i*2]=H[h[i]>>4];o[i*2+1]=H[h[i]&0xf];} o[64]='\0';
}

static DWORD find_pid(const wchar_t* name) {
    HANDLE s=CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS,0); if(s==INVALID_HANDLE_VALUE)return 0;
    PROCESSENTRY32W pe; memset(&pe,0,sizeof(pe)); pe.dwSize=sizeof(pe); DWORD pid=0;
    if(Process32FirstW(s,&pe)) do{ if(_wcsicmp(pe.szExeFile,name)==0){pid=pe.th32ProcessID;break;} }while(Process32NextW(s,&pe));
    CloseHandle(s); return pid;
}
static uint64_t mod_base(HANDLE hP) {
    HMODULE m[16]; DWORD need=0;
    if(!EnumProcessModules(hP,m,sizeof(m),&need))return 0;
    MODULEINFO mi; memset(&mi,0,sizeof(mi));
    GetModuleInformation(hP,m[0],&mi,sizeof(mi));
    return (uint64_t)(uintptr_t)mi.lpBaseOfDll;
}
static BOOL rd(HANDLE hP,uint64_t vma,void*dst,size_t n){
    SIZE_T g=0; return ReadProcessMemory(hP,(LPCVOID)(uintptr_t)vma,dst,n,&g)&&g==n;
}
static BOOL wr(HANDLE hP,uint64_t vma,const void*src,size_t n){
    DWORD old=0; if(!VirtualProtectEx(hP,(LPVOID)(uintptr_t)vma,n,PAGE_EXECUTE_READWRITE,&old))return FALSE;
    SIZE_T w=0; BOOL ok=WriteProcessMemory(hP,(LPVOID)(uintptr_t)vma,src,n,&w)&&w==n;
    VirtualProtectEx(hP,(LPVOID)(uintptr_t)vma,n,old,&old); return ok;
}

// ---- state.json ----
static void path_next_to_exe(char* dst, size_t dstsz, const char* fname) {
    GetModuleFileNameA(NULL, dst, (DWORD)dstsz);
    char* p = strrchr(dst, '\\'); if (p) *(p+1)='\0'; else dst[0]='\0';
    StringCchCatA(dst, dstsz, fname);
}

static void write_state(const char* path, const char* sha,
                        const uint8_t co[8], const uint8_t s1[4], const uint8_t s2[4],
                        double interval) {
    FILE* f=fopen(path,"w"); if(!f)return;
    fprintf(f,"{\n  \"eu4_sha256\":\"%s\",\n  \"tip_interval_seconds\":%.6f,\n",sha,interval);
    fprintf(f,"  \"cave_original\":[%d",co[0]); for(int i=1;i<8;i++)fprintf(f,",%d",co[i]); fprintf(f,"],\n");
    fprintf(f,"  \"site1_original\":[%d",s1[0]); for(int i=1;i<4;i++)fprintf(f,",%d",s1[i]); fprintf(f,"],\n");
    fprintf(f,"  \"site2_original\":[%d",s2[0]); for(int i=1;i<4;i++)fprintf(f,",%d",s2[i]); fprintf(f,"]\n}\n");
    fclose(f);
}

// ---- modes ----
static int do_apply(void) {
    char cpath[MAX_PATH], spath[MAX_PATH];
    path_next_to_exe(cpath, sizeof(cpath), "config.json");
    path_next_to_exe(spath, sizeof(spath), "state.json");

    double interval = 0.0;
    int rc = json_get_double(cpath, "tip_interval_seconds", &interval);
    if (rc != 0 || interval <= 0.0) {
        fprintf(stderr, "error: tip_interval_seconds missing/invalid in config.json (need > 0)\n");
        return 2;
    }
    fprintf(stderr, "config: tip_interval_seconds = %.6f\n", interval);

    DWORD pid = find_pid(L"eu4.exe");
    if (!pid) { fprintf(stderr, "error: eu4.exe not running. Launch EU4 first.\n"); return 3; }
    fprintf(stderr, "eu4.exe PID = %lu\n", pid);

    uint8_t hash[32];
    if (sha256_file(EU4_EXE_W, hash) != 0) { fprintf(stderr, "error: sha256 failed\n"); return 4; }
    char hex[65]; to_hex(hash, hex);
    fprintf(stderr, "eu4.exe sha256: %s\n", hex);

    HANDLE hP = OpenProcess(PROCESS_VM_READ|PROCESS_VM_WRITE|PROCESS_VM_OPERATION|PROCESS_QUERY_INFORMATION, FALSE, pid);
    if (!hP) { fprintf(stderr, "OpenProcess failed: %lu\n", GetLastError()); return 5; }

    uint64_t base = mod_base(hP);
    int64_t delta = (int64_t)(base - PREFERRED_BASE);
    fprintf(stderr, "actual base 0x%llx, ASLR delta %+lld\n", (unsigned long long)base, (long long)delta);

    uint64_t cave  = CAVE_VMA        + delta;
    uint64_t s1    = SITE1_MOVSD_VMA + delta;
    uint64_t s2    = SITE2_MOVSD_VMA + delta;

    // Read original bytes (for revert).
    uint8_t co[8], s1o[4], s2o[4];
    if (!rd(hP, cave,   co, 8)) { fprintf(stderr,"read cave failed: %lu\n",GetLastError()); CloseHandle(hP); return 6; }
    if (!rd(hP, s1 + 4, s1o, 4)) { fprintf(stderr,"read site1 failed\n"); CloseHandle(hP); return 6; }
    if (!rd(hP, s2 + 4, s2o, 4)) { fprintf(stderr,"read site2 failed\n"); CloseHandle(hP); return 6; }

    // Sanity: confirm originals match expected.
    if (memcmp(s1o, SITE1_ORIG, 4) != 0) {
        fprintf(stderr, "WARN: site1 bytes != expected. got %02x %02x %02x %02x\n", s1o[0],s1o[1],s1o[2],s1o[3]);
        fprintf(stderr, "      eu4.exe may be a different version. Aborting.\n");
        CloseHandle(hP); return 7;
    }
    if (memcmp(s2o, SITE2_ORIG, 4) != 0) {
        fprintf(stderr, "WARN: site2 bytes != expected. got %02x %02x %02x %02x\n", s2o[0],s2o[1],s2o[2],s2o[3]);
        CloseHandle(hP); return 7;
    }

    // 1. Write user's double into the code cave.
    double iv = interval;
    if (!wr(hP, cave, &iv, 8)) { fprintf(stderr,"write cave failed\n"); CloseHandle(hP); return 8; }
    fprintf(stderr, "wrote %.6f to code cave @ 0x%llx\n", interval, (unsigned long long)cave);

    // 2. Repoint site1 disp32.
    if (!wr(hP, s1 + 4, SITE1_NEW, 4)) { fprintf(stderr,"write site1 failed\n"); CloseHandle(hP); return 8; }
    fprintf(stderr, "patched site1 disp32 @ 0x%llx\n", (unsigned long long)(s1+4));

    // 3. Repoint site2 disp32.
    if (!wr(hP, s2 + 4, SITE2_NEW, 4)) { fprintf(stderr,"write site2 failed\n"); CloseHandle(hP); return 8; }
    fprintf(stderr, "patched site2 disp32 @ 0x%llx\n", (unsigned long long)(s2+4));

    write_state(spath, hex, co, s1o, s2o, interval);
    fprintf(stderr, "OK: loading-screen cycle interval -> %.1f s. state saved to state.json\n", interval);
    CloseHandle(hP);
    return 0;
}

static int do_revert(void) {
    char spath[MAX_PATH]; path_next_to_exe(spath, sizeof(spath), "state.json");
    DWORD pid = find_pid(L"eu4.exe");
    if (!pid) { fprintf(stderr, "eu4.exe not running\n"); return 3; }
    HANDLE hP = OpenProcess(PROCESS_VM_READ|PROCESS_VM_WRITE|PROCESS_VM_OPERATION|PROCESS_QUERY_INFORMATION, FALSE, pid);
    if (!hP) { fprintf(stderr, "OpenProcess failed\n"); return 5; }
    uint64_t base = mod_base(hP);
    int64_t delta = (int64_t)(base - PREFERRED_BASE);
    uint64_t cave = CAVE_VMA + delta, s1 = SITE1_MOVSD_VMA + delta, s2 = SITE2_MOVSD_VMA + delta;

    // Read state.json for original bytes. (Simple parse.)
    FILE* f = fopen(spath, "r"); if (!f) { fprintf(stderr, "no state.json\n"); CloseHandle(hP); return 9; }
    char sb[4096]; size_t n = fread(sb, 1, sizeof(sb)-1, f); sb[n]='\0'; fclose(f);
    // Parse the three arrays by finding '[' after each key.
    uint8_t co[8], s1o[4], s2o[4];
    char* p1 = strstr(sb, "cave_original");   char* b1 = strchr(p1, '[');
    char* p2 = strstr(sb, "site1_original");  char* b2 = strchr(p2, '[');
    char* p3 = strstr(sb, "site2_original");  char* b3 = strchr(p3, '[');
    for (int i = 0; i < 8; i++) co[i]  = (uint8_t)strtol(b1 + (i? strchr(b1,',')+1 - b1 : 1), &b1, 10);
    for (int i = 0; i < 4; i++) s1o[i] = (uint8_t)strtol(b2 + (i? strchr(b2,',')+1 - b2 : 1), &b2, 10);
    for (int i = 0; i < 4; i++) s2o[i] = (uint8_t)strtol(b3 + (i? strchr(b3,',')+1 - b3 : 1), &b3, 10);

    wr(hP, cave,   co,  8);
    wr(hP, s1 + 4, s1o, 4);
    wr(hP, s2 + 4, s2o, 4);
    fprintf(stderr, "reverted: restored original bytes at all 3 sites\n");
    CloseHandle(hP);
    return 0;
}

static int do_status(void) {
    char spath[MAX_PATH]; path_next_to_exe(spath, sizeof(spath), "state.json");
    FILE* f = fopen(spath, "r"); if (!f) { fprintf(stderr, "no state.json (not patched?)\n"); return 0; }
    char line[256];
    while (fgets(line, sizeof(line), f)) printf("  %s", line);
    fclose(f);
    return 0;
}

// ---- launcher: CREATE_SUSPENDED + patch + resume ----
// This is the correct way: the movsd instructions run once during loading-screen
// setup, so the patch MUST be in place before EU4 executes its first instruction.
// CREATE_SUSPENDED maps eu4.exe into memory but halts before entry point; we
// patch there, then resume. Not a debugger (BeingDebugged=0), so anti-debug
// startup checks don't fire.
static int do_launch(void) {
    char cpath[MAX_PATH]; path_next_to_exe(cpath, sizeof(cpath), "config.json");
    char lpath[MAX_PATH]; path_next_to_exe(lpath, sizeof(lpath), "launch.log");
    FILE* lf = fopen(lpath, "w");
    #define LOG(...) do { fprintf(stderr, __VA_ARGS__); fprintf(stderr, "\n"); \
                          if (lf) { fprintf(lf, __VA_ARGS__); fprintf(lf, "\n"); fflush(lf); } } while(0)
    double interval = 0.0;
    if (json_get_double(cpath, "tip_interval_seconds", &interval) != 0 || interval <= 0.0) {
        LOG("error: tip_interval_seconds missing/invalid in config.json");
        if (lf) fclose(lf);
        return 2;
    }
    LOG("config: tip_interval_seconds = %.6f", interval);

    STARTUPINFOA si; memset(&si, 0, sizeof(si)); si.cb = sizeof(si);
    PROCESS_INFORMATION pi; memset(&pi, 0, sizeof(pi));
    char cmdline[1024]; snprintf(cmdline, sizeof(cmdline), "\"%s\"", EU4_EXE);
    if (!CreateProcessA(EU4_EXE, cmdline, NULL, NULL, FALSE,
                        CREATE_SUSPENDED, NULL,
                        "C:\\Program Files (x86)\\Steam\\steamapps\\common\\Europa Universalis IV",
                        &si, &pi)) {
        LOG("CreateProcess failed: %lu", GetLastError());
        if (lf) fclose(lf);
        return 10;
    }
    LOG("launched eu4.exe PID %lu (suspended)", pi.dwProcessId);

    HANDLE hP = pi.hProcess;

    // Give the loader a moment to map modules even though suspended.
    Sleep(50);

    // Resolve base. Try EnumProcessModules first, then PEB.
    uint64_t base = mod_base(hP);
    LOG("EnumProcessModules base = 0x%llx", (unsigned long long)base);
    if (base == 0) {
        typedef LONG (WINAPI *pNtQIP)(HANDLE, ULONG, PVOID, ULONG, PULONG);
        HMODULE ntdll = GetModuleHandleW(L"ntdll.dll");
        pNtQIP NtQIP = (pNtQIP)GetProcAddress(ntdll, "NtQueryInformationProcess");
        LOG("NtQIP ptr = %p", (void*)NtQIP);
        if (NtQIP) {
            // PROCESS_BASIC_INFORMATION (x64): ExitStatus(4)+pad(4), PebBase(8), ...
            unsigned char pbi[48]; memset(pbi, 0, sizeof(pbi)); ULONG ret = 0;
            LONG st = NtQIP(hP, 0, pbi, sizeof(pbi), &ret);
            LOG("NtQIP status = %ld, returned %lu bytes", st, ret);
            uint64_t peb = *(uint64_t*)(pbi + 8);  // PebBaseAddress at offset 8
            LOG("PEB = 0x%llx", (unsigned long long)peb);
            if (peb) {
                uint64_t imgbase = 0; SIZE_T g = 0;
                BOOL ok = ReadProcessMemory(hP, (LPCVOID)(peb + 0x10), &imgbase, 8, &g);
                LOG("PEB ImageBaseAddress read: ok=%d g=%llu imgbase=0x%llx", ok, (unsigned long long)g, (unsigned long long)imgbase);
                base = imgbase;
            }
        }
    }
    if (base == 0) {
        LOG("error: cannot resolve eu4.exe base. killing process.");
        TerminateProcess(hP, 0); CloseHandle(hP); CloseHandle(pi.hThread);
        if (lf) fclose(lf);
        return 11;
    }
    int64_t delta = (int64_t)(base - PREFERRED_BASE);
    LOG("actual base 0x%llx, delta %+lld", (unsigned long long)base, (long long)delta);

    uint64_t cave = CAVE_VMA + delta, s1 = SITE1_MOVSD_VMA + delta, s2 = SITE2_MOVSD_VMA + delta;
    LOG("cave=0x%llx site1=0x%llx site2=0x%llx",
        (unsigned long long)cave, (unsigned long long)s1, (unsigned long long)s2);

    // Verify sites.
    uint8_t chk1[4], chk2[4];
    BOOL r1 = rd(hP, s1+4, chk1, 4);
    BOOL r2 = rd(hP, s2+4, chk2, 4);
    LOG("read site1: ok=%d bytes=%02x%02x%02x%02x", r1, chk1[0],chk1[1],chk1[2],chk1[3]);
    LOG("read site2: ok=%d bytes=%02x%02x%02x%02x", r2, chk2[0],chk2[1],chk2[2],chk2[3]);
    if (!r1 || memcmp(chk1, SITE1_ORIG, 4) != 0) {
        LOG("error: site1 mismatch (eu4.exe version?). killing.");
        TerminateProcess(hP, 0); CloseHandle(hP); CloseHandle(pi.hThread);
        if (lf) fclose(lf);
        return 12;
    }
    if (!r2 || memcmp(chk2, SITE2_ORIG, 4) != 0) {
        LOG("error: site2 mismatch (eu4.exe version?). killing.");
        TerminateProcess(hP, 0); CloseHandle(hP); CloseHandle(pi.hThread);
        if (lf) fclose(lf);
        return 12;
    }

    // 1. Write user's double into code cave.
    double iv = interval;
    BOOL w0 = wr(hP, cave, &iv, 8);
    LOG("write cave (8 bytes double): ok=%d err=%lu", w0, GetLastError());
    // 2. Repoint sites.
    BOOL w1 = wr(hP, s1+4, SITE1_NEW, 4);
    BOOL w2 = wr(hP, s2+4, SITE2_NEW, 4);
    LOG("write site1 disp32: ok=%d err=%lu", w1, GetLastError());
    LOG("write site2 disp32: ok=%d err=%lu", w2, GetLastError());
    if (!w0 || !w1 || !w2) {
        LOG("error: a write failed. killing.");
        TerminateProcess(hP, 0); CloseHandle(hP); CloseHandle(pi.hThread);
        if (lf) fclose(lf);
        return 13;
    }

    // Save state.
    uint8_t co[8]; memset(co, 0xCC, 8);
    uint8_t hash[32]; char hex[65] = {0};
    if (sha256_file(EU4_EXE_W, hash) == 0) to_hex(hash, hex);
    char spath[MAX_PATH]; path_next_to_exe(spath, sizeof(spath), "state.json");
    write_state(spath, hex, co, SITE1_ORIG, SITE2_ORIG, interval);
    LOG("state saved.");

    // Resume.
    DWORD prev = ResumeThread(pi.hThread);
    LOG("ResumeThread: prev suspend count = %lu", prev);
    CloseHandle(pi.hThread);
    CloseHandle(hP);
    LOG("OK: eu4.exe running with loading-tip interval = %.1f s", interval);
    if (lf) fclose(lf);
    return 0;
}

int main(int argc, char** argv) {
    const char* mode = (argc >= 2) ? argv[1] : "--launch";
    if (strcmp(mode, "--launch") == 0)  return do_launch();
    if (strcmp(mode, "--apply") == 0)   return do_apply();
    if (strcmp(mode, "--revert") == 0)  return do_revert();
    if (strcmp(mode, "--status") == 0)  return do_status();
    fprintf(stderr, "Usage: loading_tip_patcher.exe [--launch|--apply|--revert|--status]\n");
    fprintf(stderr, "  --launch (default): CREATE_SUSPENDED eu4.exe, patch, resume\n");
    return 1;
}