/* sheetjs (C) 2013-present  SheetJS -- https://sheetjs.com */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "duktape.h"

#define FAIL_LOAD { \
  duk_push_undefined(ctx); \
  perror("Error in load_file"); \
  return 1; \
}

static char *read_file(const char *filename, size_t *sz) {
  FILE *f = fopen(filename, "rb");
  if(!f) return NULL;
  long fsize; { fseek(f, 0, SEEK_END); fsize = ftell(f); fseek(f, 0, SEEK_SET); }
  char *buf = (char *)malloc(fsize * sizeof(char));
  *sz = fread((void *) buf, 1, fsize, f);
  fclose(f);
  return buf;
}

static duk_int_t eval_file(duk_context *ctx, const char *filename) {
  size_t len; char *buf = read_file(filename, &len);
  if(!buf) FAIL_LOAD

  duk_push_lstring(ctx, (const char *)buf, (duk_size_t)len);
  duk_int_t retval = duk_peval(ctx);
  duk_pop(ctx);
  return retval;
}

static duk_int_t load_file(duk_context *ctx, const char *filename, const char *var) {
  size_t len; char *buf = read_file(filename, &len);
  if(!buf) FAIL_LOAD

  duk_push_external_buffer(ctx);
  duk_config_buffer(ctx, -1, buf, len);
  duk_put_global_string(ctx, var);
  return 0;
}

static duk_int_t save_file(duk_context *ctx, const char *filename, const char *var) {
  duk_get_global_string(ctx, var);
  duk_size_t sz;
  char *buf = (char *)duk_get_buffer_data(ctx, -1, &sz);

  if(!buf) return 1;
  FILE *f = fopen(filename, "wb"); fwrite(buf, 1, sz, f); fclose(f);
  return 0;
}

#define FAIL(cmd) { \
  printf("error in %s: %s\n", cmd, duk_safe_to_string(ctx, -1)); \
  duk_destroy_heap(ctx); \
  return res; \
}

#define DOIT(cmd) duk_eval_string_noresult(ctx, cmd);
int main(int argc, char *argv[]) {
  duk_int_t res = 0;

  /* initialize */
  duk_context *ctx = duk_create_heap_default();
  /* duktape does not expose a standard "global" by default */
  DOIT("var global = (function(){ return this; }).call(null);");

  /* load library */
  res = eval_file(ctx, "shim.min.js");
  if(res != 0) FAIL("shim load")
  res = eval_file(ctx, "xlsx.full.min.js");
  if(res != 0) FAIL("library load")

  /* get version string */
  duk_eval_string(ctx, "XLSX.version");
  printf("SheetJS library version %s\n", duk_get_string(ctx, -1));
  duk_pop(ctx);

  /* read file */
  res = load_file(ctx, argv[1], "buf");
  if(res != 0) FAIL("file load")
  printf("Loaded file %s\n", argv[1]);

  /* parse workbook */
  DOIT("wb = XLSX.read(buf.slice(0, buf.length), {type:'buffer'});");
  DOIT("ws = wb.Sheets[wb.SheetNames[0]]");

  /* print CSV */
  duk_eval_string(ctx, "XLSX.utils.sheet_to_csv(ws)");
  printf("%s\n", duk_get_string(ctx, -1));
  duk_pop(ctx);

  /* write file */
#define WRITE_TYPE(BOOKTYPE) \
  DOIT("newbuf = (XLSX.write(wb, {type:'array', bookType:'" BOOKTYPE "'}));");\
  res = save_file(ctx, "sheetjsw." BOOKTYPE, "newbuf");\
  if(res != 0) FAIL("save sheetjsw." BOOKTYPE)

  WRITE_TYPE("xlsb")

  /* cleanup */
  duk_destroy_heap(ctx);
  return res;
}