/* DE1: $Id: dd_help.c 2838 2006-02-16 22:50:13Z danij $
 * Copyright (C) 2003, 2004 Jaakko Keränen <jaakko.keranen@iki.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not: http://www.opensource.org/
 */

/*
 * dd_help.c: Help Text Strings
 */

// HEADER FILES ------------------------------------------------------------

#include "de_base.h"
#include "de_console.h"
#include "de_system.h"
#include "de_misc.h"

// MACROS ------------------------------------------------------------------

#define MAX_STRINGS 16

// TYPES -------------------------------------------------------------------

typedef struct helpstring_s {
    int     type;
    char   *text;
} helpstring_t;

typedef struct helpnode_s {
    struct helpnode_s *prev, *next;
    char   *id;
    helpstring_t str[MAX_STRINGS];
} helpnode_t;

// EXTERNAL FUNCTION PROTOTYPES --------------------------------------------

// PUBLIC FUNCTION PROTOTYPES ----------------------------------------------

// PRIVATE FUNCTION PROTOTYPES ---------------------------------------------

// EXTERNAL DATA DECLARATIONS ----------------------------------------------

// PUBLIC DATA DEFINITIONS -------------------------------------------------

// PRIVATE DATA DEFINITIONS ------------------------------------------------

static boolean helpInited = false;
static helpnode_t helpRoot;

// CODE --------------------------------------------------------------------

/*
 * Create and link.
 */
helpnode_t* DH_NewNode(void)
{
    helpnode_t *n = calloc(sizeof(*n), 1);

    n->next = &helpRoot;
    n->prev = helpRoot.prev;
    helpRoot.prev = n->prev->next = n;
    return n;
}

/*
 * Unlink and destroy.
 */
void DH_DeleteNode(helpnode_t * node)
{
    int     i;

    node->prev->next = node->next;
    node->next->prev = node->prev;
    // Free all memory associated with the node.
    free(node->id);
    for(i = 0; i < MAX_STRINGS; i++)
        free(node->str[i].text);
    free(node);
}

int DH_ReadStrings(char *fileName)
{
    DFILE  *file = F_Open(fileName, "rt");
    char    line[2048], *ptr, *eol, *end;
    helpnode_t *node = NULL;
    int     count, length;

    if(!file)
    {
        Con_Message("DH_ReadStrings: %s not found.\n", fileName);
        return false;           // The file was not found.
    }

    while(!deof(file))
    {
        M_ReadLine(line, sizeof(line), file);
        if(M_IsComment(line))
            continue;
        // Where does the line begin?
        ptr = M_SkipWhite(line);
        if(!*ptr)
            continue;           // An empty line.
        eol = ptr + strlen(ptr);    // End of line.
        // A new node?
        if(*ptr == '[')
        {
            node = DH_NewNode();
            count = 0;
            if(!(end = strchr(ptr, ']')))
                end = eol;
            node->id = calloc(end - ptr, 1);
            strncpy(node->id, ptr + 1, end - ptr - 1);
        }
        else if(node && (end = strchr(ptr, '=')))   // It must be a key?
        {
            helpstring_t *hst = node->str + count;

            if(count == MAX_STRINGS)
                continue;       // No more room.
            count++;
            // The type of the string.
            if(!strnicmp(ptr, "des", 3))
                hst->type = HST_DESCRIPTION;
            else if(!strnicmp(ptr, "cv", 2))
                hst->type = HST_CONSOLE_VARIABLE;
            else if(!strnicmp(ptr, "def", 3))
                hst->type = HST_DEFAULT_VALUE;
            ptr = M_SkipWhite(end + 1);
            // The value may be split over multiple lines.
            // 64 kb should be quite enough.
            length = 0, hst->text = malloc(0x10000);
            while(*ptr)
            {
                // Backslash escapes.
                if(*ptr == '\\')
                {
                    // Is this the last visible char?
                    if(!*M_SkipWhite(ptr + 1))
                    {
                        // Read the next line.
                        M_ReadLine(line, sizeof(line), file);
                        ptr = M_SkipWhite(line);
                    }
                    else        // \ is not the last char on the line.
                    {
                        ptr++;
                        if(*ptr == '\\')
                            hst->text[length++] = '\\';
                        if(*ptr == 'n')
                            hst->text[length++] = '\n';
                        if(*ptr == 'b')
                            hst->text[length++] = '\b';
                        ptr++;
                    }
                }
                else
                {
                    // Append to the text.
                    hst->text[length++] = *ptr++;
                }
            }
            // Resize the memory to fit the text.
            hst->text[length] = 0;
            hst->text = realloc(hst->text, length + 1);
        }
    }

    // The file was read successfully.
    F_Close(file);
    return true;
}

/*
 * Finds a node matching the ID. Use DH_GetString to read strings from it.
 */
void* DH_Find(char *id)
{
    helpnode_t *n;

    if(!helpInited)
        return NULL;
    for(n = helpRoot.next; n != &helpRoot; n = n->next)
        if(!strnicmp(id, n->id, strlen(n->id)))
            return n;
    return NULL;
}

char* DH_GetString(void *foundNode, int type)
{
    helpnode_t *n = foundNode;
    int     i;

    if(!n || !helpInited)
        return NULL;
    for(i = 0; i < MAX_STRINGS; i++)
        if(n->str[i].text && n->str[i].type == type)
            return n->str[i].text;
    return NULL;
}

void DD_InitHelp(void)
{
    char    helpFileName[256];

    if(helpInited)
        return;

    // Init the links.
    helpRoot.next = helpRoot.prev = &helpRoot;

    // Control Panel help.
    M_TranslatePath("}Data\\CPHelp.txt", helpFileName);
    DH_ReadStrings(helpFileName);

    // Help is now available.
    helpInited = true;
}

void DD_ShutdownHelp(void)
{
    if(!helpInited)
        return;
    helpInited = false;
    // Delete all the nodes.
    while(helpRoot.next != &helpRoot)
        DH_DeleteNode(helpRoot.next);
}