#include <lunaix/mm/page.h>
#include <lunaix/process.h>
#include <lunaix/spike.h>
#include <lunaix/syslog.h>
#include <lunaix/trace.h>

#include <sys/abi.h>
#include <sys/mm/mm_defs.h>
#include <sys/trace.h>

#include <klibc/string.h>

#define NB_TRACEBACK 16

LOG_MODULE("TRACE")

static struct trace_context trace_ctx;

void
trace_modksyms_init(struct boot_handoff* bhctx)
{
    struct boot_modent* modents = bhctx->mods.entries;
    for (size_t i = 0; i < bhctx->mods.mods_num; i++) {
        struct boot_modent* mod = &bhctx->mods.entries[i];
        if (streq(mod->str, "modksyms")) {
            assert(!va_offset(mod->start));

            pte_t pte = mkpte(mod->start, KERNEL_DATA);
            size_t n = pfn(mod->end) - pfn(mod->start);
            
            ptr_t ksym_va = vmap_leaf_ptes(pte, n);

            assert(ksym_va);
            trace_ctx.ksym_table = (struct ksyms*)ksym_va;
        }
    }
}

struct ksym_entry*
trace_sym_lookup(ptr_t addr)
{
    int c = trace_ctx.ksym_table->ksym_count;
    struct ksym_entry* ksent = trace_ctx.ksym_table->syms;

    int i = c - 1, j = 0, m = 0;

    if (addr > ksent[i].pc || addr < ksent[j].pc || !kernel_addr(addr)) {
        return NULL;
    }

    while (i - j != 1) {
        m = (i + j) / 2;
        if (ksent[m].pc > addr) {
            i = m;
        } else if (ksent[m].pc < addr) {
            j = m;
        } else {
            break;
        }
    }

    struct ksym_entry* result = &ksent[MIN(i, j)];
    if (result->pc > addr) {
        return NULL;
    }

    return result;
}

static char*
ksym_getstr(struct ksym_entry* sym)
{
    if (!sym) {
        return "???";
    }

    return (char*)((ptr_t)trace_ctx.ksym_table +
                   trace_ctx.ksym_table->ksym_label_off + sym->label_off);
}

static inline bool valid_fp(ptr_t ptr) {
    ptr_t start = ROUNDUP(current_thread->kstack - KSTACK_SIZE, MEM_PAGE);

    return (start < ptr && ptr < current_thread->kstack) 
           || arch_valid_fp(ptr);
}

int
trace_walkback(struct trace_record* tb_buffer,
               ptr_t fp,
               int limit,
               ptr_t* last_fp)
{
    ptr_t* frame = (ptr_t*)fp;
    struct ksym_entry* current = NULL;
    int i = 0;

    while (valid_fp((ptr_t)frame) && i < limit) {
        ptr_t pc = abi_get_retaddrat((ptr_t)frame);

        current = trace_sym_lookup(pc);
        tb_buffer[i] =
          (struct trace_record){ .pc = pc,
                                 .sym_pc = current ? current->pc : 0,
                                 .symbol = ksym_getstr(current) };

        frame = (ptr_t*)*frame;
        i++;
    }

    if (!valid_fp((ptr_t)frame)) {
        frame = NULL;
    }

    if (last_fp) {
        *last_fp = (ptr_t)frame;
    }

    return i;
}

static inline void
trace_print_code_entry(ptr_t sym_pc, ptr_t inst_pc, char* sym)
{
    if (sym_pc) {
        DEBUG("%p+%p: %s", sym_pc, inst_pc - sym_pc, sym);
    } else {
        DEBUG("%p+%p: %s", inst_pc, sym_pc, sym);
    }
}

void
trace_printstack_of(ptr_t fp)
{
    struct trace_record tbs[NB_TRACEBACK];

    // Let's get our Stackwalker does his job ;)
    int n = trace_walkback(tbs, fp, NB_TRACEBACK, &fp);

    if (fp) {
        DEBUG("...<truncated>");
    }

    for (int i = 0; i < n; i++) {
        struct trace_record* tb = &tbs[i];
        trace_print_code_entry(tb->sym_pc, tb->pc, tb->symbol);
    }
}

void
trace_printstack()
{
    if (current_thread) {
        trace_printstack_isr(current_thread->intr_ctx);
    }
    else {
        trace_printstack_of(abi_get_callframe());
    }
}

static void
trace_printswctx(const isr_param* p, bool from_usr, bool to_usr)
{

    struct ksym_entry* sym = trace_sym_lookup(p->execp->eip);

    DEBUG("^^^^^ --- %s", to_usr ? "user" : "kernel");
    DEBUG("  interrupted on #%d, ecode=%p",
          p->execp->vector,
          p->execp->err_code);
    DEBUG("vvvvv --- %s", from_usr ? "user" : "kernel");

    ptr_t sym_pc = sym ? sym->pc : p->execp->eip;
    trace_print_code_entry(sym_pc, p->execp->eip, ksym_getstr(sym));
}

void
trace_printstack_isr(const isr_param* isrm)
{
    isr_param* p = isrm;
    ptr_t fp = abi_get_callframe();
    int prev_usrctx = 0;

    DEBUG("stack trace (pid=%d)\n", __current->pid);

    trace_printstack_of(fp);

    while (p) {
        if (!prev_usrctx) {
            if (!kernel_context(p)) {
                trace_printswctx(p, true, false);
            } else {
                trace_printswctx(p, false, false);
            }
        } else {
            trace_printswctx(p, false, true);
        }

        fp = saved_fp(p);
        if (!valid_fp(fp)) {
            DEBUG("??? invalid frame: %p", fp);
            break;
        }

        trace_printstack_of(fp);

        prev_usrctx = !kernel_context(p);

        p = p->execp->saved_prev_ctx;
    }

    DEBUG("----- [trace end] -----\n");
}