#include <stdio.h>
#include <string.h>
#include <sys/stat.h>

#include <gst/gstconfig.h>

#include <glib.h>


typedef struct {
  gchar *name;
  GSList *srcpads;
  GSList *sinkpads;
  GSList *srcpadtemplates;
  GSList *sinkpadtemplates;
  GSList *arguments;
} comp_element;

enum {
  ARG_INT,
  ARG_FILENAME,
  ARG_ENUM
};

typedef struct {
  gchar *name;
  int type;
  GSList *enums;
} comp_argument;

typedef struct {
  gint value;
  gchar *nick;
} enum_value;


void print_match_list (gchar *prefix, int len, GSList *wordlist) {
  GSList *words = wordlist;

  while (words) {
    if (!len || !strncmp((gchar *)(words->data), prefix, len))
      printf("%s\n",(gchar *)(words->data));
    words = g_slist_next (words);
  }
}

int match_element (comp_element *element, gchar *name) {
  return strcmp(element->name,name);
}

int main(int argc,char *argv[]) {
  xmlDocPtr doc;
  xmlNodePtr rootnode, elementnode, propnode, argnode;
  GList *element_list = NULL;
  comp_element *element;
  GSList *element_names = NULL;
  comp_argument *argument;
  enum_value *option;

  gchar *prev_word = argv[3];
  gchar *partial_word = argv[2];
  int partial_len;
  GList *elements;
  GSList *pads;
  int num_pads;
  GSList *args;
  gchar *word;
  GSList *words = NULL;

  struct stat stat_buf;
  
  partial_len = strlen(partial_word);

  /***** Loading the completion information from the registry *****/

  if (stat (GST_CONFIG_DIR"/compreg.xml", &stat_buf) == 0) {
    doc = xmlParseFile (GST_CONFIG_DIR"/compreg.xml");
  } else {
    exit (1);
  }
  rootnode = doc->xmlRootNode;

  elementnode = rootnode->xmlChildrenNode;
  while (elementnode) {
    if (!strcmp(elementnode->name, "element")) {
      element = g_new0(comp_element,1);
      propnode = elementnode->xmlChildrenNode;
      while (propnode) {

        if (!strcmp(propnode->name, "name")) {
          element->name = xmlNodeGetContent(propnode);
/* fprintf(stderr,element->name); */
        } else if (!strcmp(propnode->name, "srcpad")) {
          element->srcpads = g_slist_prepend(element->srcpads, xmlNodeGetContent(propnode));
/* fprintf(stderr,"."); */
        } else if (!strcmp(propnode->name, "sinkpad")) {
          element->sinkpads = g_slist_prepend(element->sinkpads, xmlNodeGetContent(propnode));
        } else if (!strcmp(propnode->name, "srcpadtemplate")) {
          element->srcpadtemplates = g_slist_prepend(element->srcpadtemplates, xmlNodeGetContent(propnode));
/* fprintf(stderr,"."); */
        } else if (!strcmp(propnode->name, "sinkpad")) {
          element->sinkpadtemplates = g_slist_prepend(element->sinkpadtemplates, xmlNodeGetContent(propnode));
        } else if (!strcmp(propnode->name, "argument")) {
          argument = g_new0(comp_argument,1);
          argument->name = xmlNodeGetContent(propnode);
          argument->type = ARG_INT;

          /* walk through the values data */
          argnode = propnode->xmlChildrenNode;
          while (argnode) {
            if (!strcmp(argnode->name, "filename")) {
              argument->type = ARG_FILENAME;
            } else if (!strcmp(argnode->name,"option")) {
              argument->type = ARG_ENUM;
              option = g_new0(enum_value,1);
              sscanf(xmlNodeGetContent(argnode),"%d",&option->value);
              argument->enums = g_slist_prepend (argument->enums, option);
            }
            argnode = argnode->next;
          }

          element->arguments = g_slist_prepend(element->arguments, argument);
        }

        propnode = propnode->next;
      }
      element_list = g_list_prepend(element_list, element);
      element_names = g_slist_prepend(element_names, element->name);
    }
    elementnode = elementnode->next;
  }



  /***** Completion *****/

  /* The bulk of the work is in deciding exactly which words are an option. */

  /* if we're right at the beginning, with -launch in the first word */
  if (strstr(prev_word,"-launch")) {
    /* print out only elements with no sink pad or padtemplate */
    elements = element_list;
    while (elements) {
      element = (comp_element *)(elements->data);
      if (!element->sinkpads && !element->sinkpadtemplates)
        words = g_slist_prepend (words, element->name);
      elements = g_list_next(elements);
    }
  }

  /* if the previous word is a connection */
  if (strchr(prev_word, '!')) {
    /* print out oly elements with a sink pad or template */
    elements = element_list;
    while (elements) {
      element = (comp_element *)(elements->data);
      if (element->sinkpads || element->sinkpadtemplates)
        words = g_slist_prepend (words, element->name);
      elements = g_list_next (elements);
    }
  }

  /* if the partial word is an argument, and it's an enum */
  if (strchr(prev_word,'=')) {
    fprintf(stderr,"it's an arg, but dunno what element yet\n");
  }

  /* if the previous word is an element, we need to list both pads and arguments*/
  if ((elements = g_list_find_custom(element_list, prev_word, (GCompareFunc)match_element))) {
    element = elements->data;
    /* zero the numpads list so we can count them */
    num_pads = 0;

    /* pads */
    pads = element->srcpads;
    while (pads) {
      num_pads++;
      words = g_slist_prepend (words, g_strdup_printf("%s!",(gchar *)(pads->data)));
      pads = g_slist_next (pads);
    }

    /* padtemplates */
    pads = element->srcpadtemplates;
    while (pads) {
      num_pads++;
      word = g_strdup_printf("%s!",(gchar *)(pads->data));
      if (!g_slist_find_custom(words,word,(GCompareFunc)strcmp))
        words = g_slist_prepend (words, word);
      pads = g_slist_next (pads);
    }

    /* if there is only one pad, add '!' to the list of completions */
    if (num_pads == 1) {
      words = g_slist_prepend (words, "!");
    }

    /* arguments */
    args = element->arguments;
    while (args) {
      argument = (comp_argument *)(args->data);
      word = strstr(argument->name,"::")+2;
      words = g_slist_prepend (words, g_strdup_printf("%s=",word));
      words = g_slist_prepend (words, g_strdup_printf("%s=...",word));
      args = g_slist_next (args);
    }
  }


  /* The easy part is ouptuting the correct list of possibilities. */
  print_match_list (partial_word, partial_len, words);

  return 0;
}