#include "reader.h"

#include <ctype.h>
#include <ivy/asm/bin.h>
#include <ivy/asm/reader.h>
#include <ivy/status.h>
#include <stdlib.h>
#include <string.h>

static enum ivy_status decode_header(
	const struct ivy_bin_header *hdr, struct ivy_asm_object_info *out)
{
	out->obj_magic = b_i32_btoh(hdr->h_magic);
	out->obj_nr_sections = b_i16_btoh(hdr->h_table_len);
	out->obj_table_offset = b_i64_btoh(hdr->h_table_offset);

	return IVY_OK;
}

static enum ivy_status decode_table_entry(
	const struct ivy_bin_table_entry *entry, struct ivy_asm_section_info *out)
{
	out->s_type = b_i32_btoh(entry->e_type);
	out->s_offset = b_i64_btoh(entry->e_offset);
	out->s_length = b_i32_btoh(entry->e_size);

	return IVY_OK;
}

enum ivy_status ivy_asm_reader_open(FILE *in, struct ivy_asm_reader **out)
{
	struct ivy_asm_reader *reader = malloc(sizeof *reader);
	if (!reader) {
		return IVY_ERR_NO_MEMORY;
	}

	memset(reader, 0x0, sizeof *reader);

	reader->r_fp = in;

	fseek(in, 0, SEEK_SET);

	struct ivy_bin_header hdr;
	size_t r = fread(&hdr, sizeof hdr, 1, in);

	if (r != 1) {
		free(reader);
		return IVY_ERR_IO_FAILURE;
	}

	enum ivy_status status = decode_header(&hdr, &reader->r_info);
	if (status != IVY_OK) {
		free(reader);
		return status;
	}

	if (reader->r_info.obj_magic != IVY_BIN_MAGIC) {
		free(reader);
		return IVY_ERR_BAD_FORMAT;
	}

	fseek(in, reader->r_info.obj_table_offset, SEEK_SET);

	size_t nr_sections = reader->r_info.obj_nr_sections;
	struct ivy_bin_table_entry *table = calloc(nr_sections, sizeof *table);
	if (!table) {
		free(reader);
		return IVY_ERR_NO_MEMORY;
	}

	r = fread(table, sizeof *table, nr_sections, in);
	if (r != nr_sections) {
		free(table);
		free(reader);
		return IVY_ERR_IO_FAILURE;
	}

	struct ivy_asm_section_info *sections
		= calloc(nr_sections, sizeof *sections);
	for (size_t i = 0; i < nr_sections; i++) {
		status = decode_table_entry(&table[i], &sections[i]);

		if (status != IVY_OK) {
			free(table);
			free(sections);
			free(reader);

			return status;
		}
	}

	free(table);

	reader->r_sections = sections;

	*out = reader;
	return IVY_OK;
}

enum ivy_status ivy_asm_reader_close(struct ivy_asm_reader *reader)
{
	free(reader);
	return IVY_OK;
}

const struct ivy_asm_object_info *ivy_asm_reader_get_info(
	struct ivy_asm_reader *reader)
{
	return &reader->r_info;
}

const struct ivy_asm_section_info *ivy_asm_reader_get_sections(
	struct ivy_asm_reader *reader)
{
	return reader->r_sections;
}

enum ivy_status ivy_asm_reader_open_section(
	struct ivy_asm_reader *reader, size_t index,
	struct ivy_asm_section_reader **out)
{
	if (index >= reader->r_info.obj_nr_sections) {
		return IVY_ERR_NO_ENTRY;
	}

	struct ivy_asm_section_reader *sect = malloc(sizeof *sect);
	if (!sect) {
		return IVY_ERR_NO_MEMORY;
	}

	memset(sect, 0x0, sizeof *sect);

	sect->r_parent = reader;
	sect->r_info = &reader->r_sections[index];

	*out = sect;
	return IVY_OK;
}

const struct ivy_asm_section_info *ivy_asm_section_reader_get_info(
	struct ivy_asm_section_reader *reader)
{
	return reader->r_info;
}

enum ivy_status ivy_asm_section_reader_close(struct ivy_asm_section_reader *reader)
{
	free(reader);
	return IVY_OK;
}

enum ivy_status ivy_asm_section_reader_read(
	struct ivy_asm_section_reader *reader, size_t offset, size_t count,
	void *p, size_t *nr_read)
{
	size_t object_offset = reader->r_info->s_offset + offset;
	FILE *fp = reader->r_parent->r_fp;
	fseek(fp, object_offset, SEEK_SET);
	size_t r = fread(p, 1, count, fp);

	*nr_read = r;

	return ferror(fp) ? IVY_ERR_IO_FAILURE : IVY_OK;
}

bool ivy_asm_section_type_to_string(uint32_t in, char out[5])
{
	b_i32 v = b_i32_htob(in);

	for (size_t i = 0; i < sizeof in; i++) {
		char c = v.i_bytes[i];
		if (!isgraph(c)) {
			return false;
		}

		out[i] = c;
	}

	out[4] = 0;
	return true;
}