#include <libxml2/libxml/parser.h>
#include <libxml2/libxml/tree.h>
#include <string.h>
#include <iconv.h>
#include <limits.h>

#include "calibrate.h"
#include "file_t.h"
#include "conf.h"
#include "paths.h"

#define BUFFER_SIZE 1000

static const char* paths_xml = "/.local/modetw/paths.xml";

/**
 * Convert the text encoding of a string from UTF8 to chosen encoding.
 * @return 1 if error,
 *         0 otherwise
 */
static char*
convert_text(const char *text, const char *enc, exception_t *e);

/**
 * Replace all occurrences of a given a word in string.
 */
static void
replaceAll(char *str, const char *oldWord, const char *newWord);

/**
 * Replace a string of text with another in a text file
 * @param file Absolute path to file
 * @param before before
 * @param after after
 * @return 1 if error
 *         0 otherwise
 */
static int
replace_text_encoded(const char *file, const char *before, const char *after, exception_t *e);

static char*
convert_text(const char *text, const char *enc, exception_t *e) {
  iconv_t to;
  size_t len_before, len_after;
  char *conv;
  to = iconv_open("UTF-8", enc);
  len_before = strlen(text);
  len_after = 2 * len_before;
  conv = calloc(len_after, sizeof(char));
  if (iconv(to, &text, &len_before, &conv, &len_after) < 0)
    {
      printf("Error iconv");
      return NULL;
    }
  iconv_close(iconv);
  return conv;
}

/**
 * Replace all occurrences of a given a word in string.
 */
static void
replaceAll(char *str, const char *oldWord, const char *newWord)
{
    char *pos, temp[BUFFER_SIZE];
    int index = 0;
    int owlen;

    owlen = strlen(oldWord);
    
    /* Repeat till all occurrences are replaced. */
    while ((pos = strstr(str, oldWord)) != NULL)
    {
        // Bakup current line
        strcpy(temp, str);

        // Index of current found word
        index = pos - str;

        // Terminate str after word found index
        str[index] = '\0';

        // Concatenate str with new word 
        strcat(str, newWord);
        
        // Concatenate str with remaining words after 
        // oldword found index.
        strcat(str, temp + index + owlen);
    }
}

static int
replace_text_encoded(const char *file, const char *before, const char *after, exception_t *e)
{
  FILE *fPtr, *fTemp;
    
    char buffer[BUFFER_SIZE];


    /*  Open all required files */
    fPtr  = fopen(file, "r");
    fTemp = fopen("replace.tmp", "w"); 

    /* fopen() return NULL if unable to open file in given mode. */
    if (fPtr == NULL || fTemp == NULL)
    {
        /* Unable to open file hence exit */
        printf("\nUnable to open file.\n");
        printf("Please check whether file exists and you have read/write privilege.\n");
        return 1;
    }


    /*
     * Read line from source file and write to destination 
     * file after replacing given word.
     */
    while ((fgets(buffer, BUFFER_SIZE, fPtr)) != NULL)
    {
        // Replace all occurrence of word from current line
        replaceAll(buffer, before, after);

        // After replacing write it to temp file.
        fputs(buffer, fTemp);
    }


    /* Close all files to release resource */
    fclose(fPtr);
    fclose(fTemp);


    /* Delete original source file */
    remove(file);

    /* Rename temp file as original file */
    rename("replace.tmp", file);
    return 0;
}

int calibrate(exception_t *e)
{
  /* Verify installation */
  if (verify(e) > 0)
    {
      return 1;
    }

  /* Modify text */
  if (edit(e) > 0)
    {
      return 1;
    }

  return 0;
}

int
verify(exception_t *e)
{
  xmlDoc *doc = NULL;
  xmlNode *root_element, *cur_node;
  
  doc = xmlReadFile(paths_xml, NULL, 0);
  if (doc == NULL)
    {
      e->type = XML_FILE_MISSING;
      return 1;
    }
  
  root_element = xmlDocGetRootElement (doc);

  if (strcmp((const char*) root_element->name, "paths"))
    {
      e->type = XML_READ_FILE_FAIL;
      return 1;
    }

  cur_node = root_element->children;

  if (strcmp((const char*) cur_node->name, "file_list"))
    {
      e->type = XML_READ_FILE_FAIL;
      return 1;
    }

  for (xmlNode *a_node = cur_node->children; strcmp((const char*) a_node->name, "group") != 0; a_node=a_node->next)
    {
      xmlNode *x_group_type = a_node->children;
      for (xmlNode *b_node = x_group_type->next; strcmp((const char*) b_node->name, "file") != 0; b_node=b_node->next)
	{
	  file_t *f;
	  xmlNode *x_name = b_node->children;
	  xmlNode *x_sum = x_name->next;
	  f = file_init((char*) x_name->content, FILEPATH_ABSOLUTE, e);
	  if (strcmp(f->hash_str, (char*) x_sum->content) != 0)
	    {
	      e->type = MD5SUM_VERIFY_FAIL;
	      return 1;
	    }
	}
    }
  return 0;
}

int
edit(exception_t *e)
{
  xmlDoc *doc = NULL;
  xmlNode *root_element, *cur_node;
  
  doc = xmlReadFile(paths_xml, NULL, 0);
  if (doc == NULL)
    {
      e->type = XML_FILE_MISSING;
      return 1;
    }
  
  root_element = xmlDocGetRootElement (doc);

  if (strcmp((const char*) root_element->name, "paths"))
    {
      e->type = XML_READ_FILE_FAIL;
      return 1;
    }

  cur_node = root_element->children;

  if (strcmp((const char*) cur_node->name, "edit_list"))
    {
      e->type = XML_READ_FILE_FAIL;
      return 1;
    }

  char *conf, *dir;
  size_t lendir;
  conf = ".config/modetw/modetw.conf";
  for (xmlNode *a_node = cur_node->children; strcmp((const char*) a_node->name, "group") != 0; a_node=a_node->next)
    {
      xmlNode *x_group_type = a_node->children;
      lendir = strlen((const char*) x_group_type);
      conf_verify_key(conf, (const char*) x_group_type, dir);
      for (xmlNode *b_node = x_group_type->next; strcmp((const char*) b_node->name, "edit") != 0; b_node=b_node->next)
	{
	  size_t lenpath;
	  file_t *f;
	  xmlNode *x_path = b_node->children;
	  xmlNode *x_before = x_path->next;
	  xmlNode *x_after = x_before->next;
	  xmlNode *x_type = x_after->next;
	  lenpath = strlen(x_path);
	  char fullpath[lenpath + lendir + 1];
	  strcat(fullpath, x_group_type);
	  strcat(fullpath, "/");
	  strcat(fullpath, x_path);
	  f = file_init(&fullpath, FILEPATH_ABSOLUTE, e);
	  replace_text(f, x_before, x_after, x_type, e);
	  file_close(f);
	}
    }
  return 0; 
}

int
replace_text(const char *file, const char *before, const char *after, const char *enc, exception_t *e)
{
  if (strcmp(enc, "ASCII") == 0) {
    return replace_text_encoded(file, before, after, e);
  }
  return replace_text_encoded(file, convert_text(before, enc, e), convert_text(after, enc, e), e);
}