#include "ini.h"
#include <ctype.h>
#include <stdlib.h>
#include <string.h>

enum parse_state {
  START,
  READING_KEY,
  SEEKING_EQ,
  SEEKING_VALUE,
  READING_VALUE,
  READING_SECTION_KEY,
  SEEKING_SECTION_VALUE,
  SEEKING_END_SECTION,
  READING_SECTION_VALUE,
  ACCEPT,
  REJECT
};

int parse_ini_file(FILE* f, char *out_key, size_t key_size, char *out_value, size_t value_size)
{
  char buf[512];
  while(fgets(&buf[0], sizeof(buf), f)) {
    int type = parse_ini_str(&buf[0], out_key, key_size, out_value, value_size);
    if(type != 0) {
      return type;
    }
  }
  return 0;
}

int parse_ini_str(const char* str, char *out_key, size_t key_size, char *out_value, size_t value_size)
{
  /* ignore comments */
  if(*str == ';') {
    out_key[0] = 0;
    out_value[0] = 0;
    return INI_UNKNOWN;
  }

  const char *key_start = 0;
  size_t key_len = 0;
  const char *value_start = 0;
  size_t value_len = 0;

  int type = INI_UNKNOWN;
  enum parse_state state = START;
  char quote = 0;
  char c = 0;

  do {
    c = *str;
    switch(state) {
      case START:
        if(c == '[') {
          type = INI_SECTION;
          state = READING_SECTION_KEY;
        } else if(c != '=') {
          type = INI_VALUE;
          state = READING_KEY;
          key_start = str;
          ++key_len;
        } else {
          state = REJECT;
        }
        break;
      case READING_KEY:
        if(isspace(c)) {
          state = SEEKING_EQ;
        } else if(c == '=') {
          state = SEEKING_VALUE;
        } else {
          ++key_len;
        }
        break;
      case SEEKING_EQ:
        if(c == '=') {
          state = SEEKING_VALUE;
        } else if(!isspace(c)) {
          state = REJECT;
        }
        break;
      case SEEKING_VALUE:
        if(c == '"' || c == '\'') {
          if(!value_start) {
            quote = c;
            state = READING_VALUE;
          } else {
            state = REJECT;
          }
        } else if(!isspace(c)) {
          value_start = str;
          ++value_len;
          state = READING_VALUE;
        }
        break;
      case READING_VALUE:
        if(quote == 0 && isspace(c)) {
          state = ACCEPT;
        } else if(quote && c == quote) {
          state = ACCEPT;
        } else if(c == 0) {
          state = ACCEPT;
        } else if(c) {
          if(!value_start) {
            value_start = str;
          }
          ++value_len;
        } else {
          state = REJECT;
        }
        break;
      case READING_SECTION_KEY:
        if(isspace(c)) {
          state = SEEKING_SECTION_VALUE;
        } else if(c == ']') {
          state = ACCEPT;
        } else {
          if(!key_start) {
            key_start = str;
          }
          ++key_len;
        }
        break;
      case SEEKING_SECTION_VALUE:
        if(c == '"' || c == '\'') {
          quote = c;
          state = READING_SECTION_VALUE;
        } else if(c == ']') {
          state = ACCEPT;
        } else if(!isspace(c)) {
          state = REJECT;
        }
        break;
      case READING_SECTION_VALUE:
        if(quote == 0 && isspace(c)) {
          state = SEEKING_END_SECTION;
        } else if(quote && c == quote) {
          state = SEEKING_END_SECTION;
        } else if(c == ']') {
          state = ACCEPT;
        } else if(c) {
          if(!value_start) {
            value_start = str;
          }
          ++value_len;
        } else {
          state = REJECT;
        }
        break;
      case SEEKING_END_SECTION:
        if(c == ']') {
          state = ACCEPT;
        } else if(!isspace(c)) {
          state = REJECT;
        }
        break;
      case ACCEPT:
        if(c != 0 && !isspace(c)) {
          state = REJECT;
        }
        break;
      case REJECT:
        return 0;
        break;
    }
    ++str;
  } while(c != 0 && state != REJECT);

  if(state == ACCEPT) {
    if(key_len >= key_size) {
      key_len = key_size - 1;
    }
    if(value_len >= value_size) {
      value_len = value_size - 1;
    }
    memcpy(out_key, key_start, key_len);
    memcpy(out_value, value_start, value_len);
    out_key[key_len] = 0;
    out_value[value_len] = 0;
    return type;
  } else {
    out_key[0] = 0;
    out_value[0] = 0;
  }

  return INI_UNKNOWN;
}