#undef  WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN

#include "diff.h"

#include <assert.h>
#include <windows.h>

static CONSOLE_SCREEN_BUFFER_INFO console_info;
static HANDLE console_hnd = INVALID_HANDLE_VALUE;

/*
 * These (currently hard-coded) colours specify the foreground colors to use
 * in the different context functions. E.g.:
 *   'set_color_context(HEADER_CONTEXT)' uses 'color_map[4]' which by default sets
 *   the foreground to bright white).
 *
 *  color_map[4] -> file-header color
 *  color_map[5] -> added color
 *  color_map[6] -> delete color
 *  color_map[7] -> line-number color (e.g. '@@ -49,21 +49,31 @@')
 *
 * The background color is never set.
 *
 * Note: The 'color_map[]' is remapped if 'color_palette' is used.
 *       See 'map_sgi_to_wincon()'.
 *       E.g. set the env-var "DIFF_COLORS=hd=37;1:ad=32;1:de=31;1:ln=33;1"
 *       to define the SGI. And invoke diff with '--color --palette=%DIFF_COLORS%'
 */
#define C_HEADER 4

static WORD color_map [] = {
            0, 0, 0, 0,
            7 | FOREGROUND_INTENSITY,  /* colour for HEADER_CONTEXT      -> bright white */
            2 | FOREGROUND_INTENSITY,  /* colour for ADD_CONTEXT         -> bright green */
            4 | FOREGROUND_INTENSITY,  /* colour for DELETE_CONTEXT      -> bright red */
            3 | FOREGROUND_INTENSITY   /* colour for LINE_NUMBER_CONTEXT -> bright cyan */
          };

static void map_sgi_to_wincon (const char *color_name, const char *sgi, WORD *color)
{
  int  num, a1 = 0, a2 = 0, fg = 0, bg = 0;
  WORD orig = *color;

  /* Ref. http://en.wikipedia.org/wiki/ANSI_escape_code#Colors
   */
  static WORD sgi_color_map[] = {
         0,                                                   /* ESC[30m -> Black */
         FOREGROUND_RED,                                      /* ESC[31m -> Red */
         FOREGROUND_GREEN,                                    /* ESC[32m -> Green */
         FOREGROUND_RED | FOREGROUND_GREEN,                   /* ESC[33m -> Yellow */
         FOREGROUND_BLUE,                                     /* ESC[34m -> Blue */
         FOREGROUND_RED | FOREGROUND_BLUE,                    /* ESC[35m -> Magenta */
         FOREGROUND_BLUE | FOREGROUND_GREEN,                  /* ESC[36m -> Cyan */
         FOREGROUND_RED | FOREGROUND_BLUE | FOREGROUND_GREEN  /* ESC[37m -> White */
       };

  num = sscanf (sgi, "%d;%d", &a1, &a2);

  if (num == 2)
  {
    if (a1 >= 30 && a1 <= 37)
    {
      fg = sgi_color_map [a1 - 30];
      if (a2 == 1)
         fg |= FOREGROUND_INTENSITY;
    }
    else if (a1 >= 40 && a1 <= 47)
    {
      bg = sgi_color_map [a1 - 40];
      if (a2 == 1)
         bg |= BACKGROUND_INTENSITY;
    }
  }
  else if (num == 1)
  {
    if (a1 >= 30 && a1 <= 37)
       fg = sgi_color_map [a1 - 30];
  }
  else
    return;

  if (fg)
     *color = fg | (orig & ~0xF);

  if (bg)
     *color = (bg << 4) | (orig & 0xF);
}

void init_wincon (void)
{
  BOOL okay;
  WORD background;
  char sgi [20], *env;
  int  i;

  assert (ARRAY_SIZE(color_indicator) <= ARRAY_SIZE(color_map));

  console_hnd = GetStdHandle (STD_OUTPUT_HANDLE);
  okay = (console_hnd != INVALID_HANDLE_VALUE &&
          GetConsoleScreenBufferInfo(console_hnd, &console_info));

  if (!okay || GetFileType(console_hnd) != FILE_TYPE_CHAR)
    colors_enabled = false;
  else {
    background = console_info.wAttributes & ~7;
    for (i = 4; i < ARRAY_SIZE(color_map); i++)
       color_map[i] |= background;
  }

  if (color_palette) {
    for (i = 0; i < ARRAY_SIZE(color_indicator); i++) {
      if (i < C_HEADER)
         continue;
      memset (sgi, '\0', sizeof(sgi));
      memcpy (sgi, color_indicator[i].string, color_indicator[i].len);
      map_sgi_to_wincon (indicator_name[i], sgi, &color_map[i]);
    }
  }
}

/*
 * Set console foreground and optionally background color.
 * color_map[index]: FG is in the low 4 bits.
 *                   BG is in the upper 4 bits of the BYTE.
 * If 'index == -1', set default console colour.
 */
void set_color (int index)
{
  BYTE fg, bg;
  WORD attr;

  if (index == -1)     /* restore to default colour */
  {
    attr = console_info.wAttributes;
    fg   = LOBYTE (attr);
    bg   = HIBYTE (attr);
  }
  else
  {
    attr = color_map[index];
    fg   = LOBYTE (attr);
    bg   = HIBYTE (attr);

    /*
    if (bg == (BYTE)-1)
         attr = console_info.wAttributes & ~7;
    else */ attr = bg << 4;
    attr |= fg;
  }
  SetConsoleTextAttribute (console_hnd, attr);
}