//
// Created by rick on 08-03-21.
//

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <elf.h>

#define DEBUG_INIT

#include <myke/debug/debug.h>
#include <myke/libk/libk.h>
#include <myke/libk/kprint.h>

static struct elf32_section_header *elf_headers = NULL;
static struct elf32_section_header *elf_shstrtab = NULL;
static struct elf32_section_header *elf_symtab = NULL;
static struct elf32_section_header *elf_strtab = NULL;
static uint32_t elf_header_cnt;

static const char *elf_name_symtab = ".symtab";
static const char *elf_name_strtab = ".strtab";

struct stackframe {
    struct stackframe *ebp;
    uintptr_t eip;
};

char *debug_get_shstrtab_entry(uint32_t ndx) {
    if (elf_shstrtab == NULL) {
        return NULL;
    }
    if (ndx > elf_shstrtab->sh_size) {
        return NULL;
    }
    return ((char *) elf_shstrtab->sh_addr + ndx);
}

char *debug_get_strtab_entry(uint32_t ndx) {
    if (elf_strtab == NULL) {
        return NULL;
    }
    if (ndx > elf_strtab->sh_size) {
        return NULL;
    }
    return ((char *) elf_strtab->sh_addr + ndx);
}

void debug_find_sections(uint32_t shndx) {
    elf_shstrtab = &elf_headers[shndx];
    for (uint32_t i = 0; i < elf_header_cnt; ++i) {
        struct elf32_section_header *current = &elf_headers[i];
        char *name = debug_get_shstrtab_entry(current->sh_name);
        if (name == NULL) {
            printf("Name was NULL\n");
            continue;
        }
        if (strcmp(name, elf_name_symtab) == 0) {
            elf_symtab = current;
            continue;
        }
        if (strcmp(name, elf_name_strtab) == 0) {
            elf_strtab = current;
            continue;
        }
    }
}

void debug_store_info(struct multiboot_info *info) {
    if (!(info->flags & MULTIBOOT_INFO_ELF_SHDR)) {
        return;
    }
    if (sizeof(struct elf32_section_header) != info->u.elf_sec.size) {
        k_panics("ELF size not correct");
    }
    elf_headers = calloc(info->u.elf_sec.num, sizeof(struct elf32_section_header));
    memcpy(elf_headers, (const void *) info->u.elf_sec.addr, sizeof(struct elf32_section_header) * info->u.elf_sec.num);
    elf_header_cnt = info->u.elf_sec.num;
    debug_find_sections(info->u.elf_sec.shndx);
}

struct elf32_symtab_entry *debug_get_entry_for_addr(uintptr_t addr) {
    if (elf_symtab == NULL) {
        return NULL;
    }
    struct elf32_symtab_entry *first = (struct elf32_symtab_entry *) elf_symtab->sh_addr;
    uint32_t num = elf_symtab->sh_size / sizeof(struct elf32_symtab_entry);
    for (uint32_t i = 0; i < num; ++i) {
        // only functions for now
        if (ELF32_ST_TYPE(first[i].st_info) != STT_FUNC) {
            continue;
        }
        if (addr >= first[i].st_value && addr < (first[i].st_value + first[i].st_size)) {
            return &first[i];
        }
    }
    return NULL;
}

void debug_backtrace(bool do_sync) {
    struct stackframe *frame = __builtin_frame_address(0);
    void (*printer)(const char *) = do_sync ? kprint_sync : kprint;
    printer("\n\n## Stack Trace ##\n");
    char msg[1024] = {0};
    while (frame->ebp != NULL) {
        struct elf32_symtab_entry *entry = debug_get_entry_for_addr(frame->eip);
        if (entry == NULL) {
            sprintf(msg, "#unknown (%lx)\n", frame->eip);
        } else {
            sprintf(msg, "%s (%lx)\n", debug_get_strtab_entry(entry->st_name), frame->eip);
        };
        printer(msg);
        frame = frame->ebp;
    }
    printer("\n");
}