// User application entry points for shell_native.

#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>
#include <string.h>
#include <ntlite/syscall.h>

#define MAX_CMD 256
#define MAX_PROCS 64  // Maximum number of processes we will fetch at once

// Output helpers.
static void print(const char* s) { SYS_WRITE_CONSOLE_REQUEST req = { SysSvFromCstr(s) }; SysWriteConsole(&req); }

// Opens file.
static uint32_t open_file(const char* path, uint32_t* handleOut) {
    SYS_PATH_HANDLE_REQUEST req = { SysSvFromCstr(path), handleOut };
    return SysOpenFile(&req);
}

// Creates file.
static uint32_t create_file(const char* path, uint32_t* handleOut) {
    SYS_PATH_HANDLE_REQUEST req = { SysSvFromCstr(path), handleOut };
    return SysCreateFile(&req);
}

// Opens dir.
static uint32_t open_dir(const char* path, uint32_t* handleOut) {
    SYS_PATH_HANDLE_REQUEST req = { SysSvFromCstr(path), handleOut };
    return SysOpenDir(&req);
}

// Updates cwd.
static uint32_t set_cwd(const char* path) {
    SYS_PATH_REQUEST req = { SysSvFromCstr(path) };
    return SysSetCwd(&req);
}

// Releases file.
static uint32_t delete_file(const char* path) {
    SYS_PATH_REQUEST req = { SysSvFromCstr(path) };
    return SysDeleteFile(&req);
}

// Creates process.
static uint32_t create_process(const char* path, uint32_t* handleOut, const char* cmdline) {
    SYS_CREATE_PROCESS_REQUEST req = { SysSvFromCstr(path), SysSvFromCstr(cmdline), handleOut };
    return SysCreateProcess(&req);
}

// Prints u Int.
static void printUInt(uint32_t n) {
    char buf[12]; int i = 0;
    if (n == 0) { print("0"); return; }
    while (n > 0) { buf[i++] = (char)('0' + n % 10); n /= 10; }
    while (i > 0) { char c[2] = { buf[--i], '\0' }; print(c); }
}

// Prints int.
static void printInt(int32_t n) {
    if (n < 0) { print("-"); printUInt((uint32_t)-(n + 1) + 1); }
    else { printUInt((uint32_t)n); }
}

// Prints u Int64.
static void printUInt64(uint64_t n) {
    if (n == 0) { print("0"); return; }
    char buf[20]; int i = 0;
    while (n > 0) { buf[i++] = (char)('0' + (int)(n % 10)); n /= 10; }
    while (i > 0) { char c[2] = { buf[--i], '\0' }; print(c); }
}

// Implements the u64 Digits operation.
static uint32_t u64Digits(uint64_t n) {
    uint32_t digits = 1;
    while (n >= 10u) { n /= 10u; digits++; }
    return digits;
}

// Prints spaces.
static void printSpaces(size_t count) {
    while (count--) print(" ");
}

// Prints u Int Width.
static void printUIntWidth(uint32_t n, size_t width) {
    uint32_t digits = u64Digits(n);
    if (width > digits) printSpaces(width - digits);
    printUInt(n);
}

// Prints u Int Zero Width.
static void printUIntZeroWidth(uint32_t n, size_t width) {
    uint32_t digits = u64Digits(n);
    while (width > digits) { print("0"); width--; }
    printUInt(n);
}

// Prints u Int64 Width.
static void printUInt64Width(uint64_t n, size_t width) {
    uint32_t digits = u64Digits(n);
    if (width > digits) printSpaces(width - digits);
    printUInt64(n);
}

// Prints hex32.
static void printHex32(uint32_t v) {
    static const char hex[] = "0123456789abcdef";
    char buf[9];
    for (int i = 7; i >= 0; i--) {
        buf[i] = hex[v & 0xFu];
        v >>= 4;
    }
    buf[8] = '\0';
    print(buf);
}

// Prints dir Time.
static void printDirTime(const SYS_SYSTEM_TIME* t) {
    if (!t || !(t->Flags & SYS_TIME_FLAG_VALID)) {
        print("---- -- -- --:--  ");
        return;
    }
    printUIntZeroWidth(t->Year, 4);
    print("-");
    printUIntZeroWidth(t->Month, 2);
    print("-");
    printUIntZeroWidth(t->Day, 2);
    print(" ");
    printUIntZeroWidth(t->Hour, 2);
    print(":");
    printUIntZeroWidth(t->Minute, 2);
    print("  ");
}

// Prints string Width.
static void printStringWidth(const char* s, size_t width) {
    size_t len = s ? strlen(s) : 0;
    if (s) print(s);
    if (width > len) printSpaces(width - len);
}

// Line editor.
static void readLine(char* buf, int len) {
    int pos = 0;
    while (true) {
        char c = SysReadKeyboardChar();
        if (!c) { SysYield(); continue; }
        if (c == '\r' || c == '\n') { print("\n"); break; }
        if ((c == '\b' || c == 127) && pos > 0) { pos--; print("\b \b"); continue; }
        if (c < 0x20 || c == 127) continue;
        if (pos < len - 1) { buf[pos++] = c; char echo[2] = {c, '\0'}; print(echo); }
    }
    buf[pos] = '\0';
}

// Implements the trim operation.
static char* trim(char* s) {
    while (*s == ' ') s++;
    int len = (int)strlen(s);
    while (len > 0 && s[len - 1] == ' ') len--;
    s[len] = '\0';
    return s;
}

// Built-in commands.
static void cmd_help() {
    print("Available commands:\n"
          "  help              - Show this list\n"
          "  mem               - Show memory usage\n"
          "  time              - Show system wall-clock time\n"
          "  display           - Show display provider and counters\n"
          "  stats             - Show scheduler/CPU/PMM telemetry\n"
          "  ps                - List processes\n"
          "  dir [path]        - List directory contents\n"
          "  cd <path>         - Change directory\n"
          "  type <file>       - Display file contents\n"
          "  del <file>        - Delete a file\n"
          "  write <file> <tx> - Create a file with text\n"
          "  clear             - Clear the screen\n"
          "  exit              - Close the shell\n");
}

// Prints size Ki B.
static void printSizeKiB(uint64_t bytes) {
    printUInt64(bytes / 1024u);
    print(" KiB");
}


// Prints pages Ki B.
static void printPagesKiB(uint64_t pages) {
    printUInt64(pages * 4u);
    print(" KiB");
}

// Prints cpu Flags.
static void printCpuFlags(uint32_t flags) {
    if (flags & SYS_CPU_FLAG_BSP) print("bsp ");
    if (flags & SYS_CPU_FLAG_ONLINE) print("online ");
    if (flags & SYS_CPU_FLAG_PARKED) print("parked ");
    if (flags & SYS_CPU_FLAG_PRIMARY) print("primary ");
    if (flags & SYS_CPU_FLAG_STARTED) print("started ");
    if (flags & SYS_CPU_FLAG_PRESENT) print("present ");
}

// Implements the cmd stats operation.
static void cmd_stats(void) {
    SYS_SCHEDULER_STATS sched;
    SYS_PMM_STATS pmm;
    SYS_CPU_STATS cpu;
    uint32_t status;

    status = SysQueryKernelStats(SYS_KERNEL_STATS_SCHEDULER, &sched, sizeof(sched), NULL);
    if (status != 0) {
        print("stats: scheduler query failed: ");
        printUInt(status);
        print("\n");
        return;
    }

    status = SysQueryKernelStats(SYS_KERNEL_STATS_PMM, &pmm, sizeof(pmm), NULL);
    if (status != 0) {
        print("stats: pmm query failed: ");
        printUInt(status);
        print("\n");
        return;
    }

    status = SysQueryKernelStats(SYS_KERNEL_STATS_CPU, &cpu, sizeof(cpu), NULL);
    if (status != 0) {
        print("stats: cpu query failed: ");
        printUInt(status);
        print("\n");
        return;
    }

    print("Scheduler:\n");
    print("  ticks:              "); printUInt64(sched.Ticks); print("\n");
    print("  context switches:   "); printUInt64(sched.ContextSwitches); print("\n");
    print("  quantum expires:    "); printUInt64(sched.QuantumExpirations); print("\n");
    print("  priority preempts:  "); printUInt64(sched.PriorityPreemptions); print("\n");
    print("  idle selections:    "); printUInt64(sched.IdleSelections); print("\n");
    print("  keep-current:       "); printUInt64(sched.KeepCurrentDecisions); print("\n");
    print("  demotions:          "); printUInt64(sched.Demotions); print("\n");
    print("  aging promotions:   "); printUInt64(sched.AgingPromotions); print("\n");
    print("  voluntary blocks:   "); printUInt64(sched.VoluntaryBlocks); print("\n");
    print("  SMT deferrals:      "); printUInt64(sched.SmtSiblingDeferrals); print("\n");
    print("  SMT primary pokes:  "); printUInt64(sched.SmtPrimaryPokes); print("\n");

    print("CPUs:\n");
    uint32_t n = cpu.CpuCount;
    if (n > SYS_KERNEL_STATS_MAX_CPUS)
        n = SYS_KERNEL_STATS_MAX_CPUS;
    for (uint32_t i = 0; i < n; i++) {
        SYS_CPU_STAT* c = &cpu.Cpu[i];
        print("  cpu"); printUInt(c->CpuIndex);
        print(" lapic="); printUInt(c->LapicId);
        print(" tid="); printUInt(c->CurrentTid);
        print(" ticks="); printUInt64(c->SchedulerTicks);
        print(" switches="); printUInt64(c->ContextSwitches);
        print(" flags="); printCpuFlags(c->Flags);
        print("\n");
    }

    print("Physical memory:\n");
    print("  total:              "); printPagesKiB(pmm.TotalFrames); print(" (frames="); printUInt64(pmm.TotalFrames); print(")\n");
    print("  used:               "); printPagesKiB(pmm.UsedFrames); print(" (frames="); printUInt64(pmm.UsedFrames); print(")\n");
    print("  free:               "); printPagesKiB(pmm.FreeFrames); print(" (frames="); printUInt64(pmm.FreeFrames); print(")\n");
    print("  largest free run:   "); printPagesKiB(pmm.LargestFreeRun); print(" (frames="); printUInt64(pmm.LargestFreeRun); print(")\n");
    print("  free runs:          "); printUInt64(pmm.FreeRunCount); print("\n");
    print("  run histogram:\n");
    print("    1:        "); printUInt64(pmm.FreeRunHistogram[0]); print("\n");
    print("    2-3:      "); printUInt64(pmm.FreeRunHistogram[1]); print("\n");
    print("    4-7:      "); printUInt64(pmm.FreeRunHistogram[2]); print("\n");
    print("    8-15:     "); printUInt64(pmm.FreeRunHistogram[3]); print("\n");
    print("    16-63:    "); printUInt64(pmm.FreeRunHistogram[4]); print("\n");
    print("    64-255:   "); printUInt64(pmm.FreeRunHistogram[5]); print("\n");
    print("    256-1023: "); printUInt64(pmm.FreeRunHistogram[6]); print("\n");
    print("    1024+:    "); printUInt64(pmm.FreeRunHistogram[7]); print("\n");
}


// Implements the cmd time operation.
static void cmd_time(void) {
    SYS_SYSTEM_TIME t;
    uint32_t status = SysGetSystemTime(&t);
    if (status != 0) {
        print("time: failed: ");
        printUInt(status);
        print("\n");
        return;
    }

    printUIntZeroWidth(t.Year, 4); print("-");
    printUIntZeroWidth(t.Month, 2); print("-");
    printUIntZeroWidth(t.Day, 2); print(" ");
    printUIntZeroWidth(t.Hour, 2); print(":");
    printUIntZeroWidth(t.Minute, 2); print(":");
    printUIntZeroWidth(t.Second, 2); print(".");
    printUIntZeroWidth(t.Millisecond, 3);
    print(" epoch="); printUInt64(t.EpochSeconds);
    print(" flags=0x"); printUInt(t.Flags);
    if (t.Flags & SYS_TIME_FLAG_TZ_KNOWN) {
        print(" tz="); printInt(t.TimeZoneMinutes);
    } else {
        print(" tz=unspecified");
    }
    print("\n");
}

// Prints display Caps.
static void printDisplayCaps(uint32_t caps) {
    bool any = false;
    if (caps & DISPLAY_CAP_FRAMEBUFFER) { print("framebuffer"); any = true; }
    if (caps & DISPLAY_CAP_SOFTWARE_CURSOR) { if (any) print(","); print("software-cursor"); any = true; }
    if (caps & DISPLAY_CAP_HARDWARE_CURSOR) { if (any) print(","); print("hardware-cursor"); any = true; }
    if (caps & DISPLAY_CAP_ACCEL_FILL) { if (any) print(","); print("accel-fill"); any = true; }
    if (caps & DISPLAY_CAP_ACCEL_COPY) { if (any) print(","); print("accel-copy"); any = true; }
    if (caps & DISPLAY_CAP_PRESENT_SYNC) { if (any) print(","); print("present-sync"); any = true; }
    if (caps & DISPLAY_CAP_VBLANK) { if (any) print(","); print("vblank"); any = true; }
    if (caps & DISPLAY_CAP_3D) { if (any) print(","); print("3d"); any = true; }
    if (!any) print("none");
}

// Prints display Stats.
static void printDisplayStats(const char* title, const DISPLAY_STATS* st) {
    print(title); print(":\n");
    print("  blit:        "); printUInt64(st->BlitCount); print("\n");
    print("  fill:        "); printUInt64(st->FillRectCount); print("\n");
    print("  copy:        "); printUInt64(st->CopyRectCount); print("\n");
    print("  read:        "); printUInt64(st->ReadRectCount); print("\n");
    print("  present:     "); printUInt64(st->PresentCount); print(" rects="); printUInt64(st->PresentRectCount); print("\n");
    print("  dirty:       "); printUInt64(st->DirtyRectCount); print(" all="); printUInt64(st->DirtyAllCount); print("\n");
    print("  bytes:       "); printUInt64(st->BytesCopied); print("\n");
    print("  sync:        "); printUInt64(st->SyncCount); print("\n");
    print("  cursor:      move="); printUInt64(st->CursorMoveCount);
    print(" show="); printUInt64(st->CursorShowCount);
    print(" hide="); printUInt64(st->CursorHideCount); print("\n");
}

// Implements the cmd display operation.
static void cmd_display(void) {
    SYS_DISPLAY_INFO info;
    uint32_t status = SysQueryDisplayInfo(&info);
    if (status != 0) {
        print("display: query failed: ");
        printUInt(status);
        print("\n");
        return;
    }

    print("Display:\n");
    print("  primary:     "); print(info.PrimaryName[0] ? info.PrimaryName : "?"); print("\n");
    print("  devices:     "); printUInt(info.DeviceCount); print("\n");
    print("  mode:        "); printUInt(info.Mode.Width); print("x"); printUInt(info.Mode.Height);
    print(" stride="); printUInt(info.Mode.Stride); print(" format="); printUInt((uint32_t)info.Mode.Format); print("\n");
    print("  caps:        0x"); printHex32(info.Caps); print(" ["); printDisplayCaps(info.Caps); print("]\n");
    printDisplayStats("Manager counters", &info.ManagerStats);
    printDisplayStats("Provider counters", &info.DeviceStats);
}

// Implements the cmd mem operation.
static void cmd_mem(void) {
    SYS_MEMORY_STATUS st;
    if (SysGetMemoryStatus(&st) != 0) {
        print("mem: failed\n");
        return;
    }

    print("Memory Status:\n");
    print("  Free physical: ");
    printSizeKiB(st.FreePhysicalBytes);
    print("\n  Kernel pool:   ");
    printSizeKiB(st.KernelPoolBytes);
    print("\n  User heap:     ");
    printSizeKiB(st.UserHeapBytes);
    print("\n");
}

// Processes state Name.
static const char* processStateName(uint32_t state) {
    switch (state) {
        case SYS_PROCESS_STATE_RUNNING:     return "run";
        case SYS_PROCESS_STATE_TERMINATING: return "term";
        case SYS_PROCESS_STATE_EXITED:      return "exit";
        default:                            return "?";
    }
}

// Implements the cmd ps operation.
static void cmd_ps(void) {
    SYS_PROCESS_INFO procs[MAX_PROCS];
    size_t count = 0;

    uint32_t status = SysGetProcessList(procs, MAX_PROCS, &count);
    if (status != 0) {
        print("ps: failed to retrieve process list\n");
        return;
    }

    print("Processes (Count: ");
    printUInt((uint32_t)count);
    print("):\n");
    print("  PID  State Thr Hnd Mod UserKiB ImageKiB Flags Name\n");

    size_t displayCount = count < MAX_PROCS ? count : MAX_PROCS;
    for (size_t i = 0; i < displayCount; i++) {
        SYS_PROCESS_INFO* p = &procs[i];
        char flags[5];
        size_t flagLen = 0;

        if (p->Flags & SYS_PROCESS_FLAG_SYSTEM) flags[flagLen++] = 'S';
        if (p->Flags & SYS_PROCESS_FLAG_CURRENT) flags[flagLen++] = '*';
        if (p->Flags & SYS_PROCESS_FLAG_TERMINATING) flags[flagLen++] = 'T';
        if (p->Flags & SYS_PROCESS_FLAG_EXITED) flags[flagLen++] = 'X';
        if (flagLen == 0) flags[flagLen++] = '-';
        flags[flagLen] = '\0';

        print("  ");
        printUIntWidth(p->ProcessId, 3);
        print("  ");
        printStringWidth(processStateName(p->State), 5);
        print(" ");
        printUIntWidth(p->ThreadCount, 3);
        print(" ");
        printUIntWidth(p->HandleCount, 3);
        print(" ");
        printUIntWidth(p->ModuleCount, 3);
        print(" ");
        printUInt64Width((uint64_t)p->UserCommittedBytes / 1024u, 7);
        print(" ");
        printUInt64Width((uint64_t)p->ImageSize / 1024u, 8);
        print(" ");
        printStringWidth(flags, 5);
        print(" ");
        print(p->Name);
        if (p->CurrentDirectory[0]) {
            print(" cwd=");
            print(p->CurrentDirectory);
        }
        print("\n");
    }

    if (count > MAX_PROCS) {
        print("  ... and ");
        printUInt((uint32_t)(count - MAX_PROCS));
        print(" more processes.\n");
    }
}

// Implements the cmd write operation.
static void cmd_write(const char* args) {
    char filename[MAX_CMD]; int i = 0;
    while (args[i] != ' ' && args[i] != '\0' && i < MAX_CMD - 1) {
        filename[i] = args[i]; i++;
    }
    filename[i] = '\0';
    if (args[i] == '\0' || args[i+1] == '\0') { print("write: usage: write <filename> <text>\n"); return; }
    uint32_t hFile;
    if (create_file(filename, &hFile) != 0) { print("write: could not create file\n"); return; }
    size_t written;
    SysWriteFile(hFile, args + i + 1, strlen(args + i + 1), &written);
    SysCloseHandle(hFile);
    print("File written successfully.\n");
}

// Implements the cmd dir operation.
static void cmd_dir(const char* path) {
    uint32_t hDir;
    const char* target = (path && *path != '\0') ? path : ".";
    
    if (open_dir(target, &hDir) != 0) { 
        print("dir: failed to open directory\n"); 
        return; 
    }

    SYS_DIR_ENTRY ke;
    while (SysReadDir(hDir, &ke) == 0) {
        printDirTime(&ke.LastWriteTime);

        // Corrected Attribute Check: 0x10 is the Directory bit in FAT.
        if (ke.Attr & 0x10) {
            print("<DIR> ");
        } else {
            print("      ");
        }

        print(ke.Name);
        
        // Optional: print file size for non-directories.
        if (!(ke.Attr & 0x10)) {
            print(" (");
            printUInt(ke.FileSize);
            print(" bytes)");
        }

        print("\n");
    }
    SysCloseHandle(hDir);
}

// Implements the cmd type operation.
static void cmd_type(const char* filename) {
    uint32_t hFile;
    if (open_file(filename, &hFile) != 0) { print("type: cannot open file\n"); return; }
    char buffer[512]; size_t bytesRead;
    while (SysReadFile(hFile, buffer, sizeof(buffer) - 1, &bytesRead) == 0 && bytesRead > 0) {
        buffer[bytesRead] = '\0'; print(buffer);
    }
    SysCloseHandle(hFile); print("\n");
}


// Implements the extract Program Path operation.
static bool extractProgramPath(const char* cmdline, char* out, size_t outSize) {
    if (!cmdline || !out || outSize == 0) return false;

    while (*cmdline == ' ' || *cmdline == '\t') cmdline++;
    if (*cmdline == '\0') return false;

    size_t pos = 0;
    if (*cmdline == '"') {
        cmdline++;
        while (*cmdline && *cmdline != '"' && pos + 1 < outSize)
            out[pos++] = *cmdline++;
    } else {
        while (*cmdline && *cmdline != ' ' && *cmdline != '\t' && pos + 1 < outSize)
            out[pos++] = *cmdline++;
    }

    out[pos] = '\0';
    return pos != 0;
}

// Run one command.
static int runCommand(const char* cmd) {
    if (!cmd || *cmd == '\0') return 0;
    if (strcmp(cmd, "exit") == 0) return 1;
    if (strcmp(cmd, "help") == 0) { cmd_help(); return 0; }
    if (strcmp(cmd, "clear") == 0) { SysClearScreen(0x012456); return 0; }
    if (strncmp(cmd, "crash", 5) == 0) {
        // Check the sub-option trailing "crash " (offset 6).
        if (strcmp(cmd + 6, "void") == 0) {
            // Jumping into the void.
            void (*invalid_func)(void) = NULL;
            invalid_func();
            return 0;
        }
        else if (strcmp(cmd + 6, "noncanonical") == 0) {
            // Non-canonical pointer dereference.
            volatile int *ptr = (volatile int*)0x4242424242424242ULL;
            *ptr = 1337;
            return 0;
        }
        else if (strcmp(cmd + 6, "ud2") == 0) {
            __ud2();
            return 0;
        }
        else if (strcmp(cmd + 6, "nx") == 0) {
            // NX / DEP Violation.
            unsigned char code[] = { 0xC3 }; 
            void (*execute_stack)(void) = (void (*)(void))code;
            execute_stack();
            return 0;
        }
        else if (strcmp(cmd + 6, "divzero") == 0) {
            // Division by zero.
            volatile int zero = 0;
            volatile int result = 1 / zero;
            (void)result;
            return 0;
        }
        else {
            // Default fallback if just "crash" or an unknown sub-option is passed.
            *(volatile int*)0 = 42;
            return 0;
        }
    }
    if (strcmp(cmd, "mem") == 0) { cmd_mem(); return 0; }
    if (strcmp(cmd, "time") == 0 || strcmp(cmd, "date") == 0) { cmd_time(); return 0; }
    if (strcmp(cmd, "display") == 0 || strcmp(cmd, "gpu") == 0) { cmd_display(); return 0; }
    if (strcmp(cmd, "stats") == 0 || strcmp(cmd, "telemetry") == 0) { cmd_stats(); return 0; }
    if (strcmp(cmd, "ps") == 0) { cmd_ps(); return 0; }
    if (strcmp(cmd, "dir") == 0) { cmd_dir("."); return 0; }
    if (strncmp(cmd, "dir ", 4) == 0) { cmd_dir(cmd + 4); return 0; }
    if (strncmp(cmd, "cd ", 3) == 0) { if (set_cwd(cmd + 3) != 0) print("cd: failed\n"); return 0; }
    if (strncmp(cmd, "del ", 4) == 0) { delete_file(cmd + 4); return 0; }
    if (strncmp(cmd, "type ", 5) == 0) { cmd_type(cmd + 5); return 0; }
    if (strncmp(cmd, "write ", 6) == 0) { cmd_write(cmd + 6); return 0; }

    char program[MAX_CMD];
    if (!extractProgramPath(cmd, program, sizeof(program))) return 0;

    uint32_t hProc;
    if (create_process(program, &hProc, cmd) == 0) {
        SysWaitForProcess(hProc);
        SysCloseHandle(hProc);
        while (SysPollKeyboard()) (void)SysReadKeyboardChar();
    } else { print("shell: launch failed\n"); }
    return 0;
}

// Runs the requested operation.
int main(void) {
    const char* cmdline = SysGetPeb()->CommandLine.Data;
    char lineBuf[MAX_CMD];

    print("shell: command line: ");
    print(cmdline);
    print("\n");
    print("shell: ready\n");
    while (true) {
        print("> ");
        readLine(lineBuf, MAX_CMD);
        if (runCommand(trim(lineBuf))) break;
    }
    print("shell: goodbye\n");
    SysExitProcess(0);
    return 0;
}