// kmain.c - kernel entry point
#include <stdint.h>
#include <string.h>
#include <intrin.h>
#include <boot_info.h>
#include <mm_phys.h>
#include <mm_virt.h>
#include <ob_object.h>
#include <ke_process.h>
#include <ke_thread.h>
#include <ke_sched.h>
#include <ke_idt.h>
#include <ke_irq.h>
#include <ke_syscall.h>
#include <ke_debug.h>
#include <ke_util.h>
#include <ldr_image.h>
#include <hal_api.h>
#include <io_file.h>
#include <ini_parser.h>

typedef struct {
    BOOT_INFO* bootInfo;
    const HAL_API* hal;
} SYSTEM_INIT_ARGS;

typedef KSTATUS (*DRIVER_ENTRY_FN)(const HAL_API *);

// HAL pointer cached at boot so kernel threads can reach it without
// threading a parameter through every call chain.
static const HAL_API* gKmainHal;

static int PageInBootloaderRegion(const BOOT_INFO* bootInfo, PHYSICAL_ADDRESS page) {
    for (uint32_t i = 0; i < bootInfo->MemoryMap.RegionCount; i++) {
        const MEMORY_REGION* r = &bootInfo->MemoryMap.Regions[i];
        if (r->Type != MemoryBootloader) continue;

        uintptr_t start = r->Base & PAGE_MASK;
        uintptr_t end   = (r->Base + r->Length + PAGE_SIZE - 1) & PAGE_MASK;
        if ((uintptr_t)page >= start && (uintptr_t)page < end) {
            return 1;
        }
    }
    return 0;
}

static void ReclaimBootloaderMemory(const BOOT_INFO* bootInfo) {
    // Reclaim only the raw buffers backing boot-loaded .sys modules.
    // The kernel/HAL images, page tables, and bootloader code remain live.
    for (uint32_t i = 2; i < bootInfo->ModuleCount; i++) {
        const BOOT_MODULE* mod = &bootInfo->Modules[i];
        if (!mod->PhysBase || !mod->ImageSize) continue;

        uintptr_t base = (uintptr_t)(mod->PhysBase & PAGE_MASK);
        uintptr_t end  = (uintptr_t)((mod->PhysBase + mod->ImageSize + PAGE_SIZE - 1) & PAGE_MASK);

        for (uintptr_t page = base; page < end; page += PAGE_SIZE) {
            if (!PageInBootloaderRegion(bootInfo, (PHYSICAL_ADDRESS)page)) continue;
            MmFreeFrame((PHYSICAL_ADDRESS)page);
        }
    }
}

// ---------------------------------------------------------------------------
// Phase Helper: Resolve Imports for core modules
// ---------------------------------------------------------------------------
static void ResolveSystemImports(BOOT_INFO* bootInfo) {
    // Only resolve imports for kernel.exe and hal.dll (typically indices 0 and 1).
    // The bootloader maps these, but drivers are now passed as raw physical files.
    uint32_t coreModuleCount = (bootInfo->ModuleCount > 2) ? 2 : bootInfo->ModuleCount;
    
    for (uint32_t i = 0; i < coreModuleCount; i++) {
        if (bootInfo->Modules[i].VirtBase != 0) {
            LdrResolveImports(bootInfo->Modules[i].VirtBase);
        }
    }
}

// ---------------------------------------------------------------------------
// Phase Helper: Initialize dynamically loaded .sys drivers
// ---------------------------------------------------------------------------
static void DriversIniCb(const char* section, const char* key,
                          const char* val, void* ud) {
    (void)val;
    if (!strcmp(section, "runtime")) {
        char*** pArray = (char***)ud;
        size_t len = strlen(key) + 1;
        char* keyCopy = MmAllocatePool(len);
        if (keyCopy) {
            memcpy(keyCopy, key, len);
            arr_push(*pArray, keyCopy);
        }
    }
}

static void InitializeDrivers(BOOT_INFO* bootInfo, const HAL_API* hal) {
    DbgPrint("InitializeDrivers: Initializing drivers...\n");
    
    // boot drivers (provided by the bootloader)
    for (uint32_t i = 0; i < bootInfo->ModuleCount; i++) {
        BOOT_MODULE* mod = &bootInfo->Modules[i];
        
        // Skip modules that are already mapped (Kernel/HAL) 
        // or have no physical data (invalid)
        if (mod->VirtBase != 0 || mod->PhysBase == 0) continue;

        DbgPrint("InitializeDrivers: Loading boot driver %s\n", mod->Name);

        // Calculate virtual address of the raw file in the physical window
        void* rawPeBuffer = (void*)(bootInfo->PhysicalMapBase + mod->PhysBase);

        // Map the PE image into kernel space
        uintptr_t mappedBase = 0;
        KSTATUS st = LdrLoadImage(rawPeBuffer, mod->ImageSize, &mappedBase, false);
        if (!KSUCCESS(st)) {
            DbgPrint("ERROR: Failed to map driver %s (0x%X)\n", mod->Name, st);
            continue;
        }

        // Update the struct so other modules can find it
        mod->VirtBase = mappedBase;

        // Resolve imports (can now see Kernel, HAL, and previous drivers)
        if (!KSUCCESS(LdrResolveImports(mappedBase))) {
            DbgPrint("ERROR: Failed to resolve imports for %s\n", mod->Name);
            continue;
        }

        // Register with the global module list so subsequent drivers can import from this one
        LdrRegisterModule(mod->Name, mod->VirtBase);

        // Execute Entry Point
        DRIVER_ENTRY_FN entry = (DRIVER_ENTRY_FN)LdrGetEntryPoint(mappedBase);
        if (entry) {
            KSTATUS ds = entry(hal);
            if (!KSUCCESS(ds)) {
                DbgPrint("WARNING: Driver %s returned failure status 0x%X\n", mod->Name, ds);
            }
        }
    }

    // runtime drivers
    KSTATUS s;
    FILE_OBJECT* f;

    s = IoOpenFile("drivers\\drivers.ini", &f);
    if (s != STATUS_SUCCESS) {
        KePanic("InitializeDrivers: Failed to open drivers.ini (status %d)\n", s);
    }

    uint64_t size = IoGetFileSize(f) + 1;
    char* mem = MmAllocatePool(size);
    size_t got;
    if (!KSUCCESS(IoReadFile(f, mem, size, &got))) {
        IoCloseFile(f);
        KePanic("InitializeDrivers: Failed to read drivers.ini\n");
    }
    mem[got] = '\0';

    IoCloseFile(f);

    char** runtimeKeys = NULL;
    IniParse(mem, DriversIniCb, &runtimeKeys);

    for (uint32_t i = 0; i < arr_len(runtimeKeys); i++) {
        DbgPrint("Found runtime driver: %s\n", runtimeKeys[i]);

        // Load the driver
        size_t len = strlen(runtimeKeys[i]);
        char* path = MmAllocatePool(len + 10);
        if (!path) {
            DbgPrint("KernelMain: Failed to allocate memory for driver path. How?\n");
            continue;
        }

        // memcpy maneuvers
        memcpy(path, "drivers\\", 8);
        memcpy(path + 8, runtimeKeys[i], len + 1);

        s = IoOpenFile(path, &f);
        if (s != STATUS_SUCCESS) {
            DbgPrint("InitializeDrivers: Failed to open runtime driver: %s (%s)\n", runtimeKeys[i], path);
            continue; // Skip this driver but keep going with others
        }

        MmFreePool(path);

        uint64_t drvSize = IoGetFileSize(f);
        void* drvMem = MmAllocatePool(drvSize);
        if (!KSUCCESS(IoReadFile(f, drvMem, drvSize, &got))) {
            DbgPrint("InitializeDrivers: Failed to read runtime driver: %s\n", runtimeKeys[i]);
            IoCloseFile(f);
            continue;
        }
        IoCloseFile(f);

        uintptr_t mappedBase = 0;
        if (!KSUCCESS(LdrLoadImage(drvMem, drvSize, &mappedBase, false))) { // Load into kernel space
            DbgPrint("InitializeDrivers: Failed to load runtime driver: %s\n", runtimeKeys[i]);
            MmFreePool(drvMem);
            continue;
        }
        MmFreePool(drvMem);

        if (!KSUCCESS(LdrResolveImports(mappedBase))) {
            DbgPrint("InitializeDrivers: Failed to resolve imports for runtime driver: %s\n", runtimeKeys[i]);
            continue;
        }

        DRIVER_ENTRY_FN entry = (DRIVER_ENTRY_FN)(LdrGetEntryPoint(mappedBase));

        KSTATUS ds = entry(hal);
        if (!KSUCCESS(ds)) {
            DbgPrint("InitializeDrivers: Driver %s failed to init!\n", runtimeKeys[i]);
        }
    }

    // Free the individual strings allocated via strdup in the callback
    if (runtimeKeys) {
        for (uint32_t i = 0; i < arr_len(runtimeKeys); i++) {
            if (runtimeKeys[i]) {
                MmFreePool(runtimeKeys[i]); 
            }
        }
        // Free the dynamic array structure itself
        arr_free(runtimeKeys);
    }

    // Free the file buffer
    MmFreePool(mem);
}

// ---------------------------------------------------------------------------
// Phase Helper: Load and launch a process from the filesystem.
// Returns the new PROCESS* with one reference owned by the caller.
// Returns NULL on failure.
// ---------------------------------------------------------------------------
static PROCESS* LaunchUserProcess(const char* filePath, const char* args) {
    KSTATUS s;
    FILE_OBJECT* f;

    // Read the executable file into a raw buffer.
    s = IoOpenFile(filePath, &f);
    DbgPrint("LaunchUserProcess: IoOpenFile: %d\n", s);
    if (s != STATUS_SUCCESS) {
        DbgPrint("Failed to load file: \"%s\"!\n", filePath);
        return 0;
    }

    uint64_t size = IoGetFileSize(f);
    DbgPrint("LaunchUserProcess: IoGetFileSize: %llu\n", size);

    void* mem = MmAllocateUserMemory(size);
    DbgPrint("LaunchUserProcess: MmAllocateUserMemory: 0x%llX\n", mem);
    if (!mem) {
        IoCloseFile(f);
        return 0;
    }

    size_t got = 0;
    s = IoReadFile(f, mem, size, &got);
    DbgPrint("LaunchUserProcess: IoReadFile: %d\n", s);
    IoCloseFile(f);
    if (!KSUCCESS(s)) {
        MmFreeUserMemory(mem, size);
        return 0;
    }

    // Create the process object.
    PROCESS* proc;
    THREAD* thread;

    s = KeCreateProcess(filePath, &proc);
    if (!KSUCCESS(s)) {
        DbgPrint("Failed to create process. System halted.\n");
        MmFreeUserMemory(mem, size);
        return 0;
    }
    DbgPrint("Created process (PID %u) with command line: %s\n", proc->ProcessId, filePath);

    if (args && args[0])
        strncpy(proc->Cmdline, args, sizeof(proc->Cmdline) - 1);
    else
        strncpy(proc->Cmdline, filePath, sizeof(proc->Cmdline) - 1);
    proc->Cmdline[sizeof(proc->Cmdline) - 1] = '\0';

    // proc->Cmdline is kernel pool (ffffc000...) - not readable at CPL=3.
    // Copy into user memory before handing the pointer to the initial thread.
    size_t cmdlineLen = strlen(proc->Cmdline) + 1;
    char* userCmdline = (char*)MmAllocateUserMemory(cmdlineLen);
    if (!userCmdline) {
        DbgPrint("LaunchUserProcess: Failed to allocate user cmdline buffer.\n");
        MmFreeUserMemory(mem, size);
        ObDereferenceObject(&proc->Header);
        return 0;
    }
    memcpy(userCmdline, proc->Cmdline, cmdlineLen);
    proc->UserCmdlineBase = (uintptr_t)userCmdline;
    proc->UserCmdlineSize = cmdlineLen;

    // Parse the raw PE file and map it into executable memory.
    uintptr_t imageBase = 0;
    s = LdrLoadImage(mem, size, &imageBase, true);
    MmFreeUserMemory(mem, size);
    if (!KSUCCESS(s)) {
        DbgPrint("LaunchUserProcess: LdrLoadImage failed with status: %d\n", s);
        ObDereferenceObject(&proc->Header);
        return 0;
    }

    s = LdrResolveImportsForProcess(proc, imageBase);
    if (!KSUCCESS(s)) {
        DbgPrint("LaunchUserProcess: Failed to resolve EXE imports for %s (status %d)\n", filePath, s);
        MmFreeUserMemory((void*)imageBase, LdrGetImageSize(imageBase));
        ObDereferenceObject(&proc->Header);
        return 0;
    }

    uintptr_t entryPoint = LdrGetEntryPoint(imageBase);
    DbgPrint("LaunchUserProcess: PE Image mapped! Base 0x%llx, Entry 0x%llX\n", imageBase, entryPoint);

    // Create the main thread, pointing it to the PE Entry Point.
    s = KeCreateThread(proc, (uintptr_t)entryPoint, (uintptr_t)userCmdline, PriorityNormal, &thread);
    if (!KSUCCESS(s)) {
        DbgPrint("LaunchUserProcess: Failed to create thread. Status: %d\n", s);
        MmFreeUserMemory((void*)imageBase, LdrGetImageSize(imageBase));
        ObDereferenceObject(&proc->Header);
        return 0;
    }
    proc->ImageBase = imageBase;
    proc->ImageSize = LdrGetImageSize(imageBase);
    DbgPrint("LaunchUserProcess: Thread created and queued!\n");

    // Caller owns the reference returned by KeCreateProcess.
    return proc;
}
static void PrintProcessList() {
    LIST_ENTRY* listHead = KeGetProcessList();
    LIST_ENTRY* current;

    DbgPrint("\nPID   | Name             | Threads | ExitCode\n");
    DbgPrint("---------------------------------------------\n");

    for (current = listHead->Fwd; current != listHead; current = current->Fwd) {
        // Translate the list entry back to the PROCESS structure
        PROCESS* proc = CONTAINING_RECORD(current, PROCESS, GlobalLink);

        DbgPrint("%-5u | %-16s | %-7u | %d\n", 
            proc->ProcessId, 
            proc->Name, 
            proc->ThreadCount, 
            proc->ExitCode);
    }
}

void SystemInitThread(void* arg) {
    SYSTEM_INIT_ARGS* args = (SYSTEM_INIT_ARGS*)arg;

    DbgPrint("SystemInitThread: Thread started. Igniting the system...\n");

    InitializeDrivers(args->bootInfo, args->hal);

    ResolveSystemImports(args->bootInfo);
    ReclaimBootloaderMemory(args->bootInfo);

    args->hal->Screen.Clear(0x000000);

    // Print memory status now that the system is fully alive
    DbgPrint("Memory Status:\n");
    DbgPrint("  -> Free (PMM):   %.2f MB\n", (float)MmFreeFrameCount() * PAGE_SIZE / (1024.0f * 1024.0f));
    DbgPrint("  -> Kernel Pool:  %.2f MB\n", (float)MmGetKernelPoolUsage() / (1024.0f * 1024.0f));
    DbgPrint("  -> User Heap:    %.2f MB\n", (float)MmGetUserHeapUsage() / (1024.0f * 1024.0f));

    // Launch User-Mode init.exe and restart it until it exits cleanly.
    while (true) {
        PROCESS* shellProc = LaunchUserProcess("system/init.exe", args->bootInfo->CommandLine);
        if (!shellProc) {
            DbgPrint("SystemInitThread: Failed to start system/init.exe; retrying.\n");
            KeYield();
            continue;
        }

        KeWaitForEvent(shellProc->ExitEvent);
        int exitCode = shellProc->ExitCode;
        DbgPrint("SystemInitThread: init.exe exited with code %d.\n", exitCode);
        ObDereferenceObject(&shellProc->Header);

        if (exitCode == 0) break;
        DbgPrint("SystemInitThread: Restarting init.exe.\n");
    }

    DbgPrint("SystemInitThread: init.exe completed successfully; shutting down.\n");
    gKmainHal->Power.Shutdown();
    MmFreePool(args);
}

// ---------------------------------------------------------------------------
// Main Kernel Entry
// ---------------------------------------------------------------------------
extern void KernelMain(BOOT_INFO* bootInfo) {
    //
    // Physical & Virtual Memory initialization
    //
    if (!MmInitializePhysical(&bootInfo->MemoryMap, bootInfo->PhysicalMapBase)) {
        _disable(); while (true) __halt(); // there's nothing we can do
    }

    PHYSICAL_ADDRESS pml4 = (PHYSICAL_ADDRESS)__readcr3();
    MmInitializeVirtual(pml4, 4 * 1024 * 1024 /* 4 MB initial pool */);

    //
    // CPU Architecture setup (GDT/IDT/Faults)
    //
    KeInitializeGdt();
    KeInitializeIdt();

    //
    // Register boot modules (Allows LdrGetExport to work for drivers and the HAL)
    // Note: Kept to a single call here to avoid the duplicate in your original code.
    //
    LdrRegisterModulesFromBootInfo(bootInfo);

    //
    // HAL Initialization
    //
    HAL_INIT_PARAMS halParams = {
        .PhysicalWindowBase = bootInfo->PhysicalMapBase,
        .FramebufferBase    = bootInfo->FramebufferBase,
        .FramebufferWidth   = bootInfo->FramebufferWidth,
        .FramebufferHeight  = bootInfo->FramebufferHeight,
        .FramebufferStride  = bootInfo->FramebufferStride,
        .RsdpPhysical       = bootInfo->RsdpPhysical,
        .DebugEnabled       = bootInfo->DebugEnabled
    };

    KSTATUS s = HalInitialize(&halParams);
    if (!KSUCCESS(s)) {
        _disable(); while (true) __halt(); // there's nothing we can do.
    }

    const HAL_API* hal = HalGetApi();
    gKmainHal = hal;

    KeInitDebug(hal->Screen.PrintChar, bootInfo->DebugEnabled); // Enable debug

    KeIrqInitialize(hal);

    KeIrqRegister(hal->Timer.IrqNumber,    hal->Timer.Isr);
    KeIrqRegister(hal->Keyboard.IrqNumber, hal->Keyboard.Isr);
    KeIrqRegister(hal->Mouse.IrqNumber,    hal->Mouse.Isr);

    HalRegisterScheduler(KeSchedulerTick);

    KeSyscallSetHal(hal);

    //
    // Dynamic Linking & Driver Execution
    //
    ResolveSystemImports(bootInfo);
    //InitializeDrivers(bootInfo, hal);

    //
    // Scheduler Prep & Status Update
    //
    KeInitializeScheduler();

    // Pack the arguments for the init thread
    SYSTEM_INIT_ARGS* initArgs = MmAllocatePool(sizeof(SYSTEM_INIT_ARGS));
    initArgs->bootInfo = bootInfo;
    initArgs->hal      = hal;

    // Spawn the Initialization Thread
    THREAD* initThread = (THREAD*)0;
    KSTATUS st = KeCreateKernelThread((uintptr_t)SystemInitThread, 
                                      (uintptr_t)initArgs, 
                                      PriorityNormal, &initThread);
    
    if (!KSUCCESS(st)) {
        KePanic("KernelMain: Failed to create SystemInitThread (status 0x%x)\n", st);
    }

    DbgPrint("KernelMain: Handing over to scheduler...\n");
    
    // Ignite the system!
    _enable();

    // The Idle Loop: The CPU rests here whenever all other threads are waiting on events.
    while (true) {
        __halt(); 
    }
}