#include <OS/Panic.h>
#include <OS/Log.h>
#include <Arch/CPU.h>

static const ASCII* GetExceptionClassString(UInt32 class) {
    switch (class) {
        case 0x00: return "Unknown reason";
        case 0x01: return "Trapped WFI | WFE instruction";
        case 0x07: return "Trapped SIMD | FP instruction";
        case 0x11: return "SVC from EL1";
        case 0x15: return "SVC from EL0";
        case 0x20: return "Instruction abort (LoEL)"; // User Execute Fault
        case 0x21: return "Instruction abort (CurrEL)"; // Kernel Execute Fault
        case 0x22: return "PC Alignment Fault"; // Jumped to a misaligned address
        case 0x24: return "Data abort (LoEL)"; // User Memory Fault
        case 0x25: return "Data abort (CurrEL)"; // Kernel Memory Fault
        case 0x26: return "SP Alignment Fault"; // SP must be 16-byte aligned
        case 0x3C: return "Breakpoint";
        default: return "Reserved";
    }
}

static void PrintSeparator() {
    OSLog("--------------------------------\n");
}


__attribute__((noreturn)) void OSPanicException(ExceptionsContext* frame) {
    UInt32 esr = frame->esr_el1;
    UInt32 class = (esr >> 26) & 0x3F; // Exception class (Bits 31:26)
    UInt32 length = (esr >> 25) & 0x1; // Instruction length (Bit 25)
    UInt32 syndrome = esr & 0x1FFFFFF; // Syndrome (Bits 24:0)

    PrintSeparator();
    OSLog("Kernel Panic! :(\n");
    PrintSeparator();
    OSLog("CPU Exception: %s (%d)\n", GetExceptionClassString(class), class);
    OSLog("ESR_EL1 (Syndrome): 0x%x (%d)\n", esr, syndrome);
    OSLog("Instruction pointer: 0x%x (%s)\n", frame->elr_el1, length ? "32-bit" : "64-bit");
    OSLog("CPU status: 0x%x\n", frame->spsr_el1);

    if (class == 0x25 || class == 0x24 || class == 0x20 || class == 0x21 ) {
        PrintSeparator();
        OSLog("Memory abort helper:\n");
        PrintSeparator();

        UInt64 far = CPUGetFAR();
        OSLog("Faulting address: 0x%x\n", far);

        UInt32 wnr = (syndrome >> 6) & 0x1;
        if (class == 0x24 || class == 0x25) {
            OSLog("[W] Caused by %s\n", wnr ? "WRITE" : "READ");
        } else {
            OSLog("[T] Tried to execute code from NX/Invalid memory\n");
        }


        UInt32 dfsc = syndrome & 0x3F;
        switch (dfsc & 0b111100) {
            case 0b000000: OSLog("[P] Reason: Address size fault (Bad pointer format)\n"); break;
            case 0b000100: OSLog("[P] Reason: Translation fault\n"); break;
            case 0b001100: OSLog("[P] Reason: Permission fault (Page protection violation)\n"); break;
            case 0b010000: OSLog("[P] Reason: Synchronous external abort\n"); break;
            case 0b100000: OSLog("[P] Reason: Alignment fault\n"); break;
            default:       OSLog("[P] Reason: Unknown fault code (0x%X)\n", dfsc); break;
        }
    }
    PrintSeparator();
    OSLog("Registers:\n");
    PrintSeparator();
    OSLog("x0 = 0x%X; x1 = 0x%X\n", frame->x0, frame->x1);
    OSLog("x2 = 0x%X; x3 = 0x%X\n", frame->x2, frame->x3);
    OSLog("x4 = 0x%X; x5 = 0x%X\n", frame->x4, frame->x5);
    OSLog("x6 = 0x%X; x7 = 0x%X\n", frame->x6, frame->x7);
    OSLog("x8 = 0x%X; x9 = 0x%X\n", frame->x8, frame->x9);
    OSLog("x10 = 0x%X; x11 = 0x%X\n", frame->x10, frame->x11);
    OSLog("x12 = 0x%X; x13 = 0x%X\n", frame->x12, frame->x13);
    OSLog("x14 = 0x%X; x15 = 0x%X\n", frame->x14, frame->x15);
    OSLog("x16 = 0x%X; x17 = 0x%X\n", frame->x16, frame->x17);
    OSLog("x18 = 0x%X; x19 = 0x%X\n", frame->x18, frame->x19);
    OSLog("x20 = 0x%X; x21 = 0x%X\n", frame->x20, frame->x21);
    OSLog("x22 = 0x%X; x23 = 0x%X\n", frame->x22, frame->x23);
    OSLog("x24 = 0x%X; x25 = 0x%X\n", frame->x24, frame->x25);
    OSLog("x26 = 0x%X; x27 = 0x%X\n", frame->x26, frame->x27);
    OSLog("\t\tx28 = 0x%X\n", frame->x28);
    OSLog("FP = 0x%X; LR = 0x%X\n", frame->x29, frame->x30);
    PrintSeparator();

    OSLog("System halted.\n");

    while (1) {
        CPUDisableInterrupts();
        CPUWaitForInterrupt();
    }
}