/* See LICENSE file for copyright and license details. */
#include <X11/Xft/Xft.h>
#include <X11/Xlib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "drw.h"
#include "util.h"

#define UTF_INVALID 0xFFFD
#define UTF_SIZ 4

static const unsigned char utfbyte[UTF_SIZ + 1] = {0x80, 0, 0xC0, 0xE0, 0xF0};
static const unsigned char utfmask[UTF_SIZ + 1] = {0xC0, 0x80, 0xE0, 0xF0, 0xF8};
static const long utfmin[UTF_SIZ + 1] = {0, 0, 0x80, 0x800, 0x10000};
static const long utfmax[UTF_SIZ + 1] = {0x10FFFF, 0x7F, 0x7FF, 0xFFFF, 0x10FFFF};

static long utf8decodebyte(const char c, size_t *i) {
    for (*i = 0; *i < (UTF_SIZ + 1); ++(*i))
        if (((unsigned char)c & utfmask[*i]) == utfbyte[*i])
            return (unsigned char)c & ~utfmask[*i];
    return 0;
}

static size_t utf8validate(long *u, size_t i) {
    if (!BETWEEN(*u, utfmin[i], utfmax[i]) || BETWEEN(*u, 0xD800, 0xDFFF))
        *u = UTF_INVALID;
    for (i = 1; *u > utfmax[i]; ++i)
        ;
    return i;
}

static size_t utf8decode(const char *c, long *u, size_t clen) {
    size_t i, j, len, type;
    long udecoded;

    *u = UTF_INVALID;
    if (!clen)
        return 0;
    udecoded = utf8decodebyte(c[0], &len);
    if (!BETWEEN(len, 1, UTF_SIZ))
        return 1;
    for (i = 1, j = 1; i < clen && j < len; ++i, ++j) {
        udecoded = (udecoded << 6) | utf8decodebyte(c[i], &type);
        if (type)
            return j;
    }
    if (j < len)
        return 0;
    *u = udecoded;
    utf8validate(u, len);

    return len;
}

Drw *drw_create(Display *dpy, int screen, Window root, unsigned int w, unsigned int h) {
    Drw *drw = ecalloc(1, sizeof(Drw));

    drw->dpy = dpy;
    drw->screen = screen;
    drw->root = root;
    drw->w = w;
    drw->h = h;
    drw->drawable = XCreatePixmap(dpy, root, w, h, DefaultDepth(dpy, screen));
    drw->gc = XCreateGC(dpy, root, 0, NULL);
    XSetLineAttributes(dpy, drw->gc, 1, LineSolid, CapButt, JoinMiter);

    return drw;
}

void drw_resize(Drw *drw, unsigned int w, unsigned int h) {
    if (!drw)
        return;

    drw->w = w;
    drw->h = h;
    if (drw->drawable)
        XFreePixmap(drw->dpy, drw->drawable);
    drw->drawable = XCreatePixmap(drw->dpy, drw->root, w, h, DefaultDepth(drw->dpy, drw->screen));
}

void drw_free(Drw *drw) {
    XFreePixmap(drw->dpy, drw->drawable);
    XFreeGC(drw->dpy, drw->gc);
    drw_fontset_free(drw->fonts);
    free(drw);
}

/* This function is an implementation detail. Library users should use
 * drw_fontset_create instead.
 */
static Fnt *xfont_create(Drw *drw, const char *fontname, FcPattern *fontpattern) {
    Fnt *font;
    XftFont *xfont = NULL;
    FcPattern *pattern = NULL;

    if (fontname) {
        /* Using the pattern found at font->xfont->pattern does not yield the
         * same substitution results as using the pattern returned by
         * FcNameParse; using the latter results in the desired fallback
         * behaviour whereas the former just results in missing-character
         * rectangles being drawn, at least with some fonts. */
        if (!(xfont = XftFontOpenName(drw->dpy, drw->screen, fontname))) {
            fprintf(stderr, "error, cannot load font from name: '%s'\n", fontname);
            return NULL;
        }
        if (!(pattern = FcNameParse((FcChar8 *)fontname))) {
            fprintf(stderr, "error, cannot parse font name to pattern: '%s'\n", fontname);
            XftFontClose(drw->dpy, xfont);
            return NULL;
        }
    } else if (fontpattern) {
        if (!(xfont = XftFontOpenPattern(drw->dpy, fontpattern))) {
            fprintf(stderr, "error, cannot load font from pattern.\n");
            return NULL;
        }
    } else {
        die("no font specified.");
    }

    font = ecalloc(1, sizeof(Fnt));
    font->xfont = xfont;
    font->pattern = pattern;
    font->h = xfont->ascent + xfont->descent;
    font->dpy = drw->dpy;

    return font;
}

static void xfont_free(Fnt *font) {
    if (!font)
        return;
    if (font->pattern)
        FcPatternDestroy(font->pattern);
    XftFontClose(font->dpy, font->xfont);
    free(font);
}

Fnt *drw_fontset_create(Drw *drw, const char *fonts[], size_t fontcount) {
    Fnt *cur, *ret = NULL;
    size_t i;

    if (!drw || !fonts)
        return NULL;

    for (i = 1; i <= fontcount; i++) {
        if ((cur = xfont_create(drw, fonts[fontcount - i], NULL))) {
            cur->next = ret;
            ret = cur;
        }
    }
    return (drw->fonts = ret);
}

void drw_fontset_free(Fnt *font) {
    if (font) {
        drw_fontset_free(font->next);
        xfont_free(font);
    }
}

void drw_clr_create(Drw *drw, Clr *dest, const char *clrname) {
    if (!drw || !dest || !clrname)
        return;

    if (!XftColorAllocName(drw->dpy, DefaultVisual(drw->dpy, drw->screen),
                           DefaultColormap(drw->dpy, drw->screen), clrname, dest))
        die("error, cannot allocate color '%s'", clrname);

    dest->pixel |= 0xff << 24;
}

/* Wrapper to create color schemes. The caller has to call free(3) on the
 * returned color scheme when done using it. */
Clr *drw_scm_create(Drw *drw, const char *clrnames[], size_t clrcount) {
    int i;
    Clr *ret;

    /* need at least two colors for a scheme */
    if (!drw || !clrnames || clrcount < 2 || !(ret = ecalloc(clrcount, sizeof(XftColor))))
        return NULL;

    for (i = 0; i < clrcount; i++)
        drw_clr_create(drw, &ret[i], clrnames[i]);
    return ret;
}

void drw_setfontset(Drw *drw, Fnt *set) {
    if (drw)
        drw->fonts = set;
}

void drw_setscheme(Drw *drw, Clr *scm) {
    if (drw)
        drw->scheme = scm;
}

void drw_rect(Drw *drw, int x, int y, unsigned int w, unsigned int h, int filled, int invert) {
    if (!drw || !drw->scheme)
        return;
    XSetForeground(drw->dpy, drw->gc, invert ? drw->scheme[ColBg].pixel : drw->scheme[ColFg].pixel);
    if (filled)
        XFillRectangle(drw->dpy, drw->drawable, drw->gc, x, y, w, h);
    else
        XDrawRectangle(drw->dpy, drw->drawable, drw->gc, x, y, w - 1, h - 1);
}

int drw_text(Drw *drw, int x, int y, unsigned int w, unsigned int h, unsigned int lpad,
             const char *text, int invert) {
    int i, ty, ellipsis_x = 0;
    unsigned int tmpw, ew, ellipsis_w = 0, ellipsis_len;
    XftDraw *d = NULL;
    Fnt *usedfont, *curfont, *nextfont;
    int utf8strlen, utf8charlen, render = x || y || w || h;
    long utf8codepoint = 0;
    const char *utf8str;
    FcCharSet *fccharset;
    FcPattern *fcpattern;
    FcPattern *match;
    XftResult result;
    int charexists = 0, overflow = 0;
    /* keep track of a couple codepoints for which we have no match. */
    enum { nomatches_len = 64 };
    static struct {
        long codepoint[nomatches_len];
        unsigned int idx;
    } nomatches;
    static unsigned int ellipsis_width = 0;

    if (!drw || (render && (!drw->scheme || !w)) || !text || !drw->fonts)
        return 0;

    if (!render) {
        w = invert ? invert : ~invert;
    } else {
        XSetForeground(drw->dpy, drw->gc, drw->scheme[invert ? ColFg : ColBg].pixel);
        XFillRectangle(drw->dpy, drw->drawable, drw->gc, x, y, w, h);
        d = XftDrawCreate(drw->dpy, drw->drawable, DefaultVisual(drw->dpy, drw->screen),
                          DefaultColormap(drw->dpy, drw->screen));
        x += lpad;
        w -= lpad;
    }

    usedfont = drw->fonts;
    if (!ellipsis_width && render)
        ellipsis_width = drw_fontset_getwidth(drw, "...");
    while (1) {
        ew = ellipsis_len = utf8strlen = 0;
        utf8str = text;
        nextfont = NULL;
        while (*text) {
            utf8charlen = utf8decode(text, &utf8codepoint, UTF_SIZ);
            for (curfont = drw->fonts; curfont; curfont = curfont->next) {
                charexists = charexists || XftCharExists(drw->dpy, curfont->xfont, utf8codepoint);
                if (charexists) {
                    drw_font_getexts(curfont, text, utf8charlen, &tmpw, NULL);
                    if (ew + ellipsis_width <= w) {
                        /* keep track where the ellipsis still fits */
                        ellipsis_x = x + ew;
                        ellipsis_w = w - ew;
                        ellipsis_len = utf8strlen;
                    }

                    if (ew + tmpw > w) {
                        overflow = 1;
                        /* called from drw_fontset_getwidth_clamp():
                         * it wants the width AFTER the overflow
                         */
                        if (!render)
                            x += tmpw;
                        else
                            utf8strlen = ellipsis_len;
                    } else if (curfont == usedfont) {
                        utf8strlen += utf8charlen;
                        text += utf8charlen;
                        ew += tmpw;
                    } else {
                        nextfont = curfont;
                    }
                    break;
                }
            }

            if (overflow || !charexists || nextfont)
                break;
            else
                charexists = 0;
        }

        if (utf8strlen) {
            if (render) {
                ty = y + (h - usedfont->h) / 2 + usedfont->xfont->ascent;
                XftDrawStringUtf8(d, &drw->scheme[invert ? ColBg : ColFg], usedfont->xfont, x, ty,
                                  (XftChar8 *)utf8str, utf8strlen);
            }
            x += ew;
            w -= ew;
        }
        if (render && overflow)
            drw_text(drw, ellipsis_x, y, ellipsis_w, h, 0, "...", invert);

        if (!*text || overflow) {
            break;
        } else if (nextfont) {
            charexists = 0;
            usedfont = nextfont;
        } else {
            /* Regardless of whether or not a fallback font is found, the
             * character must be drawn. */
            charexists = 1;

            for (i = 0; i < nomatches_len; ++i) {
                /* avoid calling XftFontMatch if we know we won't find a match */
                if (utf8codepoint == nomatches.codepoint[i])
                    goto no_match;
            }

            fccharset = FcCharSetCreate();
            FcCharSetAddChar(fccharset, utf8codepoint);

            if (!drw->fonts->pattern) {
                /* Refer to the comment in xfont_create for more information. */
                die("the first font in the cache must be loaded from a font string.");
            }

            fcpattern = FcPatternDuplicate(drw->fonts->pattern);
            FcPatternAddCharSet(fcpattern, FC_CHARSET, fccharset);
            FcPatternAddBool(fcpattern, FC_SCALABLE, FcTrue);

            FcConfigSubstitute(NULL, fcpattern, FcMatchPattern);
            FcDefaultSubstitute(fcpattern);
            match = XftFontMatch(drw->dpy, drw->screen, fcpattern, &result);

            FcCharSetDestroy(fccharset);
            FcPatternDestroy(fcpattern);

            if (match) {
                usedfont = xfont_create(drw, NULL, match);
                if (usedfont && XftCharExists(drw->dpy, usedfont->xfont, utf8codepoint)) {
                    for (curfont = drw->fonts; curfont->next; curfont = curfont->next)
                        ; /* NOP */
                    curfont->next = usedfont;
                } else {
                    xfont_free(usedfont);
                    nomatches.codepoint[++nomatches.idx % nomatches_len] = utf8codepoint;
                no_match:
                    usedfont = drw->fonts;
                }
            }
        }
    }
    if (d)
        XftDrawDestroy(d);

    return x + (render ? w : 0);
}

void drw_map(Drw *drw, Window win, int x, int y, unsigned int w, unsigned int h) {
    if (!drw)
        return;

    XCopyArea(drw->dpy, drw->drawable, win, drw->gc, x, y, w, h, x, y);
    XSync(drw->dpy, False);
}

unsigned int drw_fontset_getwidth(Drw *drw, const char *text) {
    if (!drw || !drw->fonts || !text)
        return 0;
    return drw_text(drw, 0, 0, 0, 0, 0, text, 0);
}

unsigned int drw_fontset_getwidth_clamp(Drw *drw, const char *text, unsigned int n) {
    unsigned int tmp = 0;
    if (drw && drw->fonts && text && n)
        tmp = drw_text(drw, 0, 0, 0, 0, 0, text, n);
    return MIN(n, tmp);
}

void drw_font_getexts(Fnt *font, const char *text, unsigned int len, unsigned int *w,
                      unsigned int *h) {
    XGlyphInfo ext;

    if (!font || !text)
        return;

    XftTextExtentsUtf8(font->dpy, font->xfont, (XftChar8 *)text, len, &ext);
    if (w)
        *w = ext.xOff;
    if (h)
        *h = font->h;
}

Cur *drw_cur_create(Drw *drw, int shape) {
    Cur *cur;

    if (!drw || !(cur = ecalloc(1, sizeof(Cur))))
        return NULL;

    cur->cursor = XCreateFontCursor(drw->dpy, shape);

    return cur;
}

void drw_cur_free(Drw *drw, Cur *cursor) {
    if (!cursor)
        return;

    XFreeCursor(drw->dpy, cursor->cursor);
    free(cursor);
}