/*
 * Simple example of parsing and printing JSON using jansson.
 *
 * SYNOPSIS:
 * $ examples/simple_parse
 * Type some JSON > [true, false, null, 1, 0.0, -0.0, "", {"name": "barney"}]
 * JSON Array of 8 elements:
 *   JSON True
 *   JSON False
 *   JSON Null
 *   JSON Integer: "1"
 *   JSON Real: 0.000000
 *   JSON Real: -0.000000
 *   JSON String: ""
 *   JSON Object of 1 pair:
 *     JSON Key: "name"
 *     JSON String: "barney"
 * 
 * Copyright (c) 2014 Robert Poor <rdpoor@gmail.com>
 *
 * Jansson is free software; you can redistribute it and/or modify
 * it under the terms of the MIT license. See LICENSE for details.
 */

#include <stdio.h>
#include <stdlib.h>
#include "jansson.h"

/* forward refs */
void print_json(json_t *root);
void print_json_aux(json_t *element, int indent);
void print_json_indent(int indent);
const char *json_plural(int count);
void print_json_object(json_t *element, int indent);
void print_json_array(json_t *element, int indent);
void print_json_string(json_t *element, int indent);
void print_json_integer(json_t *element, int indent);
void print_json_real(json_t *element, int indent);
void print_json_true(json_t *element, int indent);
void print_json_false(json_t *element, int indent);
void print_json_null(json_t *element, int indent);

void print_json(json_t *root) {
  print_json_aux(root, 0);
}

void print_json_aux(json_t *element, int indent) {
  switch json_typeof(element) {
    case JSON_OBJECT:
      print_json_object(element, indent);
      break;
    case JSON_ARRAY:
      print_json_array(element, indent);
      break;
    case JSON_STRING:
      print_json_string(element, indent);
      break;
    case JSON_INTEGER:
      print_json_integer(element, indent);
      break;
    case JSON_REAL:
      print_json_real(element, indent);;
      break;
    case JSON_TRUE:
      print_json_true(element, indent);;
      break;
    case JSON_FALSE:
      print_json_false(element, indent);;
      break;
    case JSON_NULL:
      print_json_null(element, indent);;
      break;
    default:
      fprintf(stderr, "unrecognized JSON type %d\n", json_typeof(element));
    }
}

void print_json_indent(int indent) {
  for (int i=0; i<indent; i++) { putchar(' '); }
}

const char *json_plural(int count) {
  return count == 1 ? "" : "s";
}

void print_json_object(json_t *element, int indent) {
  print_json_indent(indent);
  size_t size = json_object_size(element);
  const char *key;
  json_t *value;

  printf("JSON Object of %ld pair%s:\n", size, json_plural(size));
  json_object_foreach(element, key, value) {
    print_json_indent(indent + 2);
    printf("JSON Key: \"%s\"\n", key);
    print_json_aux(value, indent + 2);
  }

}

void print_json_array(json_t *element, int indent) {
  print_json_indent(indent);
  size_t size = json_array_size(element);

  printf("JSON Array of %ld element%s:\n", size, json_plural(size));
  for (size_t i=0; i<size; i++) {
    print_json_aux(json_array_get(element, i), indent + 2);
  }
}

void print_json_string(json_t *element, int indent) {
  print_json_indent(indent);
  printf("JSON String: \"%s\"\n", json_string_value(element));
}

void print_json_integer(json_t *element, int indent) {
  print_json_indent(indent);
  printf("JSON Integer: \"%" JSON_INTEGER_FORMAT "\"\n", json_integer_value(element));
}

void print_json_real(json_t *element, int indent) {
  print_json_indent(indent);
  printf("JSON Real: %f\n", json_real_value(element));
}

void print_json_true(json_t *element, int indent) {
  print_json_indent(indent);
  printf("JSON True\n");
}

void print_json_false(json_t *element, int indent) {
  print_json_indent(indent);
  printf("JSON False\n");
}

void print_json_null(json_t *element, int indent) {
  print_json_indent(indent);
  printf("JSON Null\n");
}

/* 
 * Parse text into a JSON object. If text is valid JSON, returns a
 * json_t structure, otherwise prints and error and returns null.
 */
json_t *load_json(const char *text) {
  json_t *root;
  json_error_t error;

  root = json_loads(text, 0, &error);

  if (root) {
    return root;
  } else {
    fprintf(stderr, "json error on line %d: %s\n", error.line, error.text);
    return (json_t *)0;
  }
}

/*
 * Print a prompt and return (by reference) a null-terminated line of
 * text.  Returns the number of characters read, including the line
 * termination char but excluding the null.
 */
int read_line(char **line) {
  size_t len = 0;               /* ignored */

  if (*line != NULL) {
    free(*line);
    *line = NULL;
  }
  printf("Type some JSON > ");
  fflush(stdout);

  return getline(line, &len, stdin);  
}

/* ================================================================
 * main
 */

int main(int argc, char *argv[]) {
  char *line = NULL;
  
  if (argc != 1) {
    fprintf(stderr, "Usage: %s\n", argv[0]);
    exit(-1);
  }

  while (read_line(&line) > 1) {

    /* parse text into JSON structure */
    json_t *root = load_json(line);

    if (root) {
      /* print and release the JSON structure */
      print_json(root);         
      json_decref(root);
    }
  }

  return 0;
}