/*
 * Copyright 2011 Sven Weidauer <sven.weidauer@gmail.com>
 *
 * This file is part of NetSurf, http://www.netsurf-browser.org/
 *
 * NetSurf 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; version 2 of the License.
 *
 * NetSurf 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, see <http://www.gnu.org/licenses/>.
 */

#import <Cocoa/Cocoa.h>

#import "utils/nsoption.h"
#import "netsurf/layout.h"
#import "netsurf/plotters.h"

#import "cocoa/coordinates.h"
#import "cocoa/plotter.h"
#import "cocoa/font.h"

static NSLayoutManager *cocoa_prepare_layout_manager(const char *string, size_t length,
    const plot_font_style_t *style);

static CGFloat cocoa_layout_width(NSLayoutManager *layout);
static CGFloat cocoa_layout_width_chars(NSLayoutManager *layout, size_t characters);
static NSUInteger cocoa_glyph_for_location(NSLayoutManager *layout, CGFloat x);
static size_t cocoa_bytes_for_characters(const char *string, size_t characters);
static NSDictionary *cocoa_font_attributes(const plot_font_style_t *style);

static NSTextStorage *cocoa_text_storage = nil;
static NSTextContainer *cocoa_text_container = nil;

static nserror cocoa_font_width(const plot_font_style_t *style,
    const char *string, size_t length,
    int *width)
{
    NSLayoutManager *layout;
    layout = cocoa_prepare_layout_manager(string, length, style);
    *width = cocoa_layout_width(layout);
    return NSERROR_OK;
}

static nserror cocoa_font_position(const plot_font_style_t *style,
    const char *string, size_t length,
    int x, size_t *char_offset, int *actual_x)
{
    NSLayoutManager *layout = cocoa_prepare_layout_manager(string, length, style);
    if (layout == nil) {
        return NSERROR_BAD_PARAMETER;
    }

    NSUInteger glyphIndex = cocoa_glyph_for_location(layout, x);
    NSUInteger chars = [layout characterIndexForGlyphAtIndex:glyphIndex];

    if (chars >= [cocoa_text_storage length])
        *char_offset = length;
    else
        *char_offset = cocoa_bytes_for_characters(string, chars);

    *actual_x = cocoa_pt_to_px(NSMaxX([layout boundingRectForGlyphRange:NSMakeRange(glyphIndex - 1, 1)
                                                        inTextContainer:cocoa_text_container]));

    return NSERROR_OK;
}

static nserror cocoa_font_split(const plot_font_style_t *style,
    const char *string, size_t length,
    int x, size_t *char_offset, int *actual_x)
{
    NSLayoutManager *layout = cocoa_prepare_layout_manager(string, length, style);
    if (layout == nil)
        return NSERROR_BAD_PARAMETER;

    NSUInteger glyphIndex = cocoa_glyph_for_location(layout, x);
    NSUInteger chars = [layout characterIndexForGlyphAtIndex:glyphIndex];

    if (chars >= [cocoa_text_storage length]) {
        *char_offset = length;
        *actual_x = cocoa_layout_width(layout);
        return NSERROR_OK;
    }

    chars = [[cocoa_text_storage string] rangeOfString:@" " options:NSBackwardsSearch range:NSMakeRange(0, chars + 1)].location;
    if (chars == NSNotFound) {
        *char_offset = 0;
        *actual_x = 0;
        return NSERROR_OK;
    }

    *char_offset = cocoa_bytes_for_characters(string, chars);
    *actual_x = cocoa_layout_width_chars(layout, chars);

    return NSERROR_OK;
}

static struct gui_layout_table layout_table = {
    .width = cocoa_font_width,
    .position = cocoa_font_position,
    .split = cocoa_font_split,
};

struct gui_layout_table *cocoa_layout_table = &layout_table;

#pragma mark -

void cocoa_draw_string(CGFloat x, CGFloat y, const char *bytes, size_t length, const plot_font_style_t *style)
{
    NSLayoutManager *layout = cocoa_prepare_layout_manager(bytes, length, style);
    if (layout == nil)
        return;

    NSFont *font = [cocoa_text_storage attribute:NSFontAttributeName atIndex:0 effectiveRange:NULL];
    CGFloat baseline = [layout defaultLineHeightForFont:font] * 3.0 / 4.0;

    NSRange glyphRange = [layout glyphRangeForTextContainer:cocoa_text_container];
    [layout drawGlyphsForGlyphRange:glyphRange atPoint:NSMakePoint(x, y - baseline)];
}

#pragma mark -

static inline CGFloat cocoa_layout_width(NSLayoutManager *layout)
{
    if (layout == nil)
        return 0.0;

    return cocoa_pt_to_px(NSWidth([layout usedRectForTextContainer:cocoa_text_container]));
}

static inline CGFloat cocoa_layout_width_chars(NSLayoutManager *layout, size_t characters)
{
    NSUInteger glyphIndex = [layout glyphIndexForCharacterAtIndex:characters];
    return cocoa_pt_to_px([layout locationForGlyphAtIndex:glyphIndex].x);
}

static inline NSUInteger cocoa_glyph_for_location(NSLayoutManager *layout, CGFloat x)
{
    CGFloat fraction = 0.0;
    NSUInteger glyphIndex = [layout glyphIndexForPoint:NSMakePoint(cocoa_px_to_pt(x), 0)
                                       inTextContainer:cocoa_text_container
                        fractionOfDistanceThroughGlyph:&fraction];
    if (fraction >= 1.0)
        ++glyphIndex;
    return glyphIndex;
}

static inline size_t cocoa_bytes_for_characters(const char *string, size_t chars)
{
    size_t offset = 0;
    while (chars-- > 0) {
        uint8_t ch = ((uint8_t *)string)[offset];

        if (0xC2 <= ch && ch <= 0xDF)
            offset += 2;
        else if (0xE0 <= ch && ch <= 0xEF)
            offset += 3;
        else if (0xF0 <= ch && ch <= 0xF4)
            offset += 4;
        else
            offset++;
    }
    return offset;
}

static NSLayoutManager *cocoa_prepare_layout_manager(const char *bytes, size_t length,
    const plot_font_style_t *style)
{
    if (NULL == bytes || 0 == length)
        return nil;

    NSString *string = [[NSString alloc] initWithBytes:bytes length:length encoding:NSUTF8StringEncoding];
    if (string == nil)
        return nil;

    static NSLayoutManager *layout = nil;
    if (nil == layout) {
        cocoa_text_container = [[NSTextContainer alloc] initWithContainerSize:NSMakeSize(CGFLOAT_MAX, CGFLOAT_MAX)];
        [cocoa_text_container setLineFragmentPadding:0];

        layout = [[NSLayoutManager alloc] init];
        [layout addTextContainer:cocoa_text_container];
    }

    static NSString *oldString = 0;
    static plot_font_style_t oldStyle = { 0, 0, 0, 0, 0, 0 };

    const bool styleChanged = memcmp(style, &oldStyle, sizeof oldStyle) != 0;

    if ([oldString isEqualToString:string] && !styleChanged) {
        return layout;
    }

    oldString = [string copy];
    oldStyle = *style;

    static NSDictionary *attributes = nil;
    if (styleChanged || attributes == nil) {
        attributes = cocoa_font_attributes(style);
    }

    cocoa_text_storage = [[NSTextStorage alloc] initWithString:string attributes:attributes];
    [cocoa_text_storage addLayoutManager:layout];

    [layout ensureLayoutForTextContainer:cocoa_text_container];

    return layout;
}

static NSString *const cocoa_font_families[PLOT_FONT_FAMILY_COUNT] = {
        [PLOT_FONT_FAMILY_SERIF] = @"Times",
    [PLOT_FONT_FAMILY_SANS_SERIF] = @"Helvetica",
    [PLOT_FONT_FAMILY_MONOSPACE] = @"Courier",
    [PLOT_FONT_FAMILY_CURSIVE] = @"Apple Chancery",
    [PLOT_FONT_FAMILY_FANTASY] = @"Marker Felt"
};

static inline NSFont *cocoa_font_get_nsfont(const plot_font_style_t *style)
{
    NSFont *font = [NSFont fontWithName:cocoa_font_families[style->family]
                                   size:(CGFloat)style->size / FONT_SIZE_SCALE];

    NSFontTraitMask traits = 0;
    if (style->flags & FONTF_ITALIC || style->flags & FONTF_OBLIQUE)
        traits |= NSItalicFontMask;
    if (style->flags & FONTF_SMALLCAPS)
        traits |= NSSmallCapsFontMask;
    if (style->weight > 400)
        traits |= NSBoldFontMask;

    if (0 != traits) {
        NSFontManager *fm = [NSFontManager sharedFontManager];
        font = [fm convertFont:font toHaveTrait:traits];
    }

    return font;
}

static inline NSDictionary *cocoa_font_attributes(const plot_font_style_t *style)
{
    return [NSDictionary dictionaryWithObjectsAndKeys:
                             cocoa_font_get_nsfont(style), NSFontAttributeName,
                         cocoa_convert_colour(style->foreground), NSForegroundColorAttributeName,
                         nil];
}