/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.pdfbox.pdmodel.font;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.PriorityQueue;
import java.util.Set;
import org.apache.fontbox.FontBoxFont;
import org.apache.fontbox.ttf.OpenTypeFont;
import org.apache.fontbox.ttf.TTFParser;
import org.apache.fontbox.ttf.TrueTypeFont;
import org.apache.fontbox.type1.Type1Font;

/**
 * Font mapper, locates non-embedded fonts via a pluggable FontProvider.
 *
 * @author John Hewson
 */
final class FontMapperImpl implements FontMapper
{
    private static final FontCache fontCache = new FontCache(); // todo: static cache isn't ideal
    private FontProvider fontProvider;
    private Map<String, FontInfo> fontInfoByName;
    private final TrueTypeFont lastResortFont;

    /** Map of PostScript name substitutes, in priority order. */
    private final Map<String, List<String>> substitutes = new HashMap<String, List<String>>();

    FontMapperImpl()
    {
        // substitutes for standard 14 fonts
        substitutes.put("Courier",
                Arrays.asList("CourierNew", "CourierNewPSMT", "LiberationMono", "NimbusMonL-Regu"));
        substitutes.put("Courier-Bold",
                Arrays.asList("CourierNewPS-BoldMT", "CourierNew-Bold", "LiberationMono-Bold",
                        "NimbusMonL-Bold"));
        substitutes.put("Courier-Oblique",
                Arrays.asList("CourierNewPS-ItalicMT","CourierNew-Italic",
                        "LiberationMono-Italic", "NimbusMonL-ReguObli"));
        substitutes.put("Courier-BoldOblique",
                Arrays.asList("CourierNewPS-BoldItalicMT","CourierNew-BoldItalic",
                        "LiberationMono-BoldItalic", "NimbusMonL-BoldObli"));
        substitutes.put("Helvetica",
                Arrays.asList("ArialMT", "Arial", "LiberationSans", "NimbusSanL-Regu"));
        substitutes.put("Helvetica-Bold",
                Arrays.asList("Arial-BoldMT", "Arial-Bold", "LiberationSans-Bold",
                        "NimbusSanL-Bold"));
        substitutes.put("Helvetica-Oblique",
                Arrays.asList("Arial-ItalicMT", "Arial-Italic", "Helvetica-Italic",
                        "LiberationSans-Italic", "NimbusSanL-ReguItal"));
        substitutes.put("Helvetica-BoldOblique",
                Arrays.asList("Arial-BoldItalicMT", "Helvetica-BoldItalic",
                        "LiberationSans-BoldItalic", "NimbusSanL-BoldItal"));
        substitutes.put("Times-Roman",
                Arrays.asList("TimesNewRomanPSMT", "TimesNewRoman", "TimesNewRomanPS",
                        "LiberationSerif", "NimbusRomNo9L-Regu"));
        substitutes.put("Times-Bold",
                Arrays.asList("TimesNewRomanPS-BoldMT", "TimesNewRomanPS-Bold",
                        "TimesNewRoman-Bold", "LiberationSerif-Bold",
                        "NimbusRomNo9L-Medi"));
        substitutes.put("Times-Italic",
                Arrays.asList("TimesNewRomanPS-ItalicMT", "TimesNewRomanPS-Italic",
                        "TimesNewRoman-Italic", "LiberationSerif-Italic",
                        "NimbusRomNo9L-ReguItal"));
        substitutes.put("Times-BoldItalic",
                Arrays.asList("TimesNewRomanPS-BoldItalicMT", "TimesNewRomanPS-BoldItalic",
                        "TimesNewRoman-BoldItalic", "LiberationSerif-BoldItalic",
                        "NimbusRomNo9L-MediItal"));
        substitutes.put("Symbol", Arrays.asList("Symbol", "SymbolMT", "StandardSymL"));
        substitutes.put("ZapfDingbats", Arrays.asList("ZapfDingbatsITC", "Dingbats", "MS-Gothic"));

        // Acrobat also uses alternative names for Standard 14 fonts, which we map to those above
        // these include names such as "Arial" and "TimesNewRoman"
        for (String baseName : Standard14Fonts.getNames())
        {
            if (!substitutes.containsKey(baseName))
            {
                String mappedName = Standard14Fonts.getMappedFontName(baseName);
                substitutes.put(baseName, copySubstitutes(mappedName));
            }
        }
        
        // -------------------------
        
        try
        {
            String ttfName = "org/apache/pdfbox/resources/ttf/LiberationSans-Regular.ttf";
            URL url = FontMapper.class.getClassLoader().getResource(ttfName);
            if (url == null)
            {
                throw new IOException("Error loading resource: " + ttfName);
            }
            InputStream ttfStream = url.openStream();
            TTFParser ttfParser = new TTFParser();
            lastResortFont = ttfParser.parse(ttfStream);
        }
        catch (IOException e)
        {
            throw new RuntimeException(e);
        }
    }

    // lazy thread safe singleton
    private static class DefaultFontProvider
    {
        private static final FontProvider INSTANCE = new FileSystemFontProvider(fontCache);
    }

    /**
     * Sets the font service provider.
     */
    public synchronized void setProvider(FontProvider fontProvider)
    {
        fontInfoByName = createFontInfoByName(fontProvider.getFontInfo());
        this.fontProvider = fontProvider;
    }

    /**
     * Returns the font service provider. Defaults to using FileSystemFontProvider.
     */
    public synchronized FontProvider getProvider()
    {
        if (fontProvider == null)
        {
            setProvider(DefaultFontProvider.INSTANCE);
        }
        return fontProvider;
    }

    /**
     * Returns the font cache associated with this FontMapper. This method is needed by
     * FontProvider subclasses.
     */
    public FontCache getFontCache()
    {
        return fontCache;
    }
    
    private Map<String, FontInfo> createFontInfoByName(List<? extends FontInfo> fontInfoList)
    {
        Map<String, FontInfo> map = new LinkedHashMap<String, FontInfo>();
        for (FontInfo info : fontInfoList)
        {
            for (String name : getPostScriptNames(info.getPostScriptName()))
            {
                map.put(name, info);
            }
        }
        return map;
    }

    /**
     * Gets alternative names, as seen in some PDFs, e.g. PDFBOX-142.
     */
    private Set<String> getPostScriptNames(String postScriptName)
    {
        Set<String> names = new HashSet<String>();
    
        // built-in PostScript name
        names.add(postScriptName);
     
        // remove hyphens (e.g. Arial-Black -> ArialBlack)
        names.add(postScriptName.replaceAll("-", ""));
     
        return names;
    }

    /**
     * Copies a list of font substitutes, adding the original font at the start of the list.
     */
    private List<String> copySubstitutes(String postScriptName)
    {
        return new ArrayList<String>(substitutes.get(postScriptName));
    }

    /**
     * Adds a top-priority substitute for the given font.
     *
     * @param match PostScript name of the font to match
     * @param replace PostScript name of the font to use as a replacement
     */
    public void addSubstitute(String match, String replace)
    {
        if (!substitutes.containsKey(match))
        {
            substitutes.put(match, new ArrayList<String>());
        }
        substitutes.get(match).add(replace);
    }

    /**
     * Returns the substitutes for a given font.
     */
    private List<String> getSubstitutes(String postScriptName)
    {
        List<String> subs = substitutes.get(postScriptName.replaceAll(" ", ""));
        if (subs != null)
        {
            return subs;
        }
        else
        {
            return Collections.emptyList();
        }
    }

    /**
     * Attempts to find a good fallback based on the font descriptor.
     */
    private String getFallbackFontName(PDFontDescriptor fontDescriptor)
    {
        String fontName;
        if (fontDescriptor != null)
        {
            // heuristic detection of bold
            boolean isBold = false;
            String name = fontDescriptor.getFontName();
            if (name != null)
            {
                String lower = fontDescriptor.getFontName().toLowerCase();
                isBold = lower.contains("bold") ||
                         lower.contains("black") ||
                         lower.contains("heavy");
            }

            // font descriptor flags should describe the style
            if (fontDescriptor.isFixedPitch())
            {
                fontName = "Courier";
                if (isBold && fontDescriptor.isItalic())
                {
                    fontName += "-BoldOblique";
                }
                else if (isBold)
                {
                    fontName += "-Bold";
                }
                else if (fontDescriptor.isItalic())
                {
                    fontName += "-Oblique";
                }
            }
            else if (fontDescriptor.isSerif())
            {
                fontName = "Times";
                if (isBold && fontDescriptor.isItalic())
                {
                    fontName += "-BoldItalic";
                }
                else if (isBold)
                {
                    fontName += "-Bold";
                }
                else if (fontDescriptor.isItalic())
                {
                    fontName += "-Italic";
                }
                else
                {
                    fontName += "-Roman";
                }
            }
            else
            {
                fontName = "Helvetica";
                if (isBold && fontDescriptor.isItalic())
                {
                    fontName += "-BoldOblique";
                }
                else if (isBold)
                {
                    fontName += "-Bold";
                }
                else if (fontDescriptor.isItalic())
                {
                    fontName += "-Oblique";
                }
            }
        }
        else
        {
            // if there is no FontDescriptor then we just fall back to Times Roman
            fontName = "Times-Roman";
        }
        return fontName;
    }

    /**
     * Finds a TrueType font with the given PostScript name, or a suitable substitute, or null.
     *
     * @param fontDescriptor FontDescriptor
     */
    @Override
    public FontMapping<TrueTypeFont> getTrueTypeFont(String baseFont,
                                                            PDFontDescriptor fontDescriptor)
    {
        TrueTypeFont ttf = (TrueTypeFont)findFont(FontFormat.TTF, baseFont);
        if (ttf != null)
        {
            return new FontMapping<TrueTypeFont>(ttf, false);
        }
        else
        {
            // fallback - todo: i.e. fuzzy match
            String fontName = getFallbackFontName(fontDescriptor);
            ttf = (TrueTypeFont) findFont(FontFormat.TTF, fontName);
            if (ttf == null)
            {
                // we have to return something here as TTFs aren't strictly required on the system
                ttf = lastResortFont;
            }
            return new FontMapping<TrueTypeFont>(ttf, true);
        }
    }

    /**
     * Finds a font with the given PostScript name, or a suitable substitute, or null. This allows
     * any font to be substituted with a PFB, TTF or OTF.
     *
     * @param fontDescriptor the FontDescriptor of the font to find
     */
    @Override
    public FontMapping<FontBoxFont> getFontBoxFont(String baseFont,
                                                          PDFontDescriptor fontDescriptor)
    {
        FontBoxFont font = findFontBoxFont(baseFont);
        if (font != null)
        {
            return new FontMapping<FontBoxFont>(font, false);
        }
        else
        {
            // fallback - todo: i.e. fuzzy match
            String fallbackName = getFallbackFontName(fontDescriptor);
            font = findFontBoxFont(fallbackName);
            if (font == null)
            {
                // we have to return something here as TTFs aren't strictly required on the system
                font = lastResortFont;
            }
            return new FontMapping<FontBoxFont>(font, true);
        }
    }

    /**
     * Finds a font with the given PostScript name, or a suitable substitute, or null.
     *
     * @param postScriptName PostScript font name
     */
    private FontBoxFont findFontBoxFont(String postScriptName)
    {
        Type1Font t1 = (Type1Font)findFont(FontFormat.PFB, postScriptName);
        if (t1 != null)
        {
            return t1;
        }

        TrueTypeFont ttf = (TrueTypeFont)findFont(FontFormat.TTF, postScriptName);
        if (ttf != null)
        {
            return ttf;
        }

        OpenTypeFont otf = (OpenTypeFont) findFont(FontFormat.OTF, postScriptName);
        if (otf != null)
        {
            return otf;
        }

        return null;
    }

    /**
     * Finds a font with the given PostScript name, or a suitable substitute, or null.
     *
     * @param postScriptName PostScript font name
     */
    private FontBoxFont findFont(FontFormat format, String postScriptName)
    {
        // handle damaged PDFs, see PDFBOX-2884
        if (postScriptName == null)
        {
            return null;
        }
        
        // make sure the font provider is initialized
        if (fontProvider == null)
        {
            getProvider();
        }

        // first try to match the PostScript name
        FontInfo info = getFont(format, postScriptName);
        if (info != null)
        {
            return info.getFont();
        }

        // remove hyphens (e.g. Arial-Black -> ArialBlack)
        info = getFont(format, postScriptName.replaceAll("-", ""));
        if (info != null)
        {
            return info.getFont();
        }

        // then try named substitutes
        for (String substituteName : getSubstitutes(postScriptName))
        {
            info = getFont(format, substituteName);
            if (info != null)
            {
                return info.getFont();
            }
        }

        // then try converting Windows names e.g. (ArialNarrow,Bold) -> (ArialNarrow-Bold)
        info = getFont(format, postScriptName.replaceAll(",", "-"));
        if (info != null)
        {
            return info.getFont();
        }

        // try appending "-Regular", works for Wingdings on windows
        info = getFont(format, postScriptName + "-Regular");
        if (info != null)
        {
            return info.getFont();
        }
        // no matches
        return null;
    }

    /**
     * Finds the named font with the given format.
     */
    private FontInfo getFont(FontFormat format, String postScriptName)
    {
        // strip subset tag (happens when we substitute a corrupt embedded font, see PDFBOX-2642)
        if (postScriptName.contains("+"))
        {
            postScriptName = postScriptName.substring(postScriptName.indexOf('+') + 1);
        }
        
        // look up the PostScript name
        FontInfo info = fontInfoByName.get(postScriptName);
        if (info != null && info.getFormat() == format)
        {
            return info;
        }
        return null;
    }
    
    /**
     * Finds a CFF CID-Keyed font with the given PostScript name, or a suitable substitute, or null.
     * This method can also map CJK fonts via their CIDSystemInfo (ROS).
     * 
     * @param fontDescriptor FontDescriptor
     * @param cidSystemInfo the CID system info, e.g. "Adobe-Japan1", if any.
     */
    @Override
    public CIDFontMapping getCIDFont(String baseFont, PDFontDescriptor fontDescriptor,
                                            PDCIDSystemInfo cidSystemInfo)
    {
        // try name match or substitute with OTF
        OpenTypeFont otf1 = (OpenTypeFont)findFont(FontFormat.OTF, baseFont);
        if (otf1 != null)
        {
            return new CIDFontMapping(otf1, null, false);
        }

        // try name match or substitute with TTF
        TrueTypeFont ttf = (TrueTypeFont)findFont(FontFormat.TTF, baseFont);
        if (ttf != null)
        {
            return new CIDFontMapping(null, ttf, false);
        }

        if (cidSystemInfo != null)
        {
            // "In Acrobat 3.0.1 and later, Type 0 fonts that use a CMap whose CIDSystemInfo
            // dictionary defines the Adobe-GB1, Adobe-CNS1 Adobe-Japan1, or Adobe-Korea1 character
            // collection can also be substituted." - Adobe Supplement to the ISO 32000

            String collection = cidSystemInfo.getRegistry() + "-" + cidSystemInfo.getOrdering();
            
            if (collection.equals("Adobe-GB1") || collection.equals("Adobe-CNS1") ||
                collection.equals("Adobe-Japan1") || collection.equals("Adobe-Korea1"))
            {
                // try automatic substitutes via character collection
                PriorityQueue<FontMatch> queue = getFontMatches(fontDescriptor, cidSystemInfo);
                FontMatch bestMatch = queue.poll();
                if (bestMatch != null)
                {
                    FontBoxFont font = bestMatch.info.getFont();
                    if (font instanceof OpenTypeFont)
                    {
                        return new CIDFontMapping((OpenTypeFont)font, null, true);
                    }
                    else if (font != null)
                    {
                        return new CIDFontMapping(null, font, true);
                    }  
                }
            }
        }

        // last-resort fallback
        return new CIDFontMapping(null, lastResortFont, true);
    }

    /**
     * Returns a list of matching fonts, scored by suitability. Positive scores indicate matches
     * for certain attributes, while negative scores indicate mismatches. Zero scores are neutral.
     * 
     * @param fontDescriptor FontDescriptor, always present.
     * @param cidSystemInfo Font's CIDSystemInfo, may be null.
     */
    private PriorityQueue<FontMatch> getFontMatches(PDFontDescriptor fontDescriptor,
                                                           PDCIDSystemInfo cidSystemInfo)
    {
        PriorityQueue<FontMatch> queue = new PriorityQueue<FontMatch>(20);
        
        for (FontInfo info : fontInfoByName.values())
        {
            // filter by CIDSystemInfo, if given
            if (cidSystemInfo != null && !isCharSetMatch(cidSystemInfo, info))
            {
                continue;
            }

            FontMatch match = new FontMatch(info);

            // Panose is the most reliable
            if (fontDescriptor.getPanose() != null && info.getPanose() != null)
            {
                PDPanoseClassification panose = fontDescriptor.getPanose().getPanose();
                if (panose.getFamilyKind() == info.getPanose().getFamilyKind())
                {
                    // serifs
                    if (panose.getSerifStyle() == info.getPanose().getSerifStyle())
                    {
                        // exact match
                        match.score += 2;
                    }
                    else if (panose.getSerifStyle() >= 2 && panose.getSerifStyle() <= 5 &&
                             info.getPanose().getSerifStyle() >= 2 &&
                             info.getPanose().getSerifStyle() <= 5)
                    {
                        // cove (serif)
                        match.score += 1;
                    }
                    else if (panose.getSerifStyle() >= 11 && panose.getSerifStyle() <= 13 &&
                             info.getPanose().getSerifStyle() >= 11 &&
                             info.getPanose().getSerifStyle() <= 13)
                    {
                        // sans-serif
                        match.score += 1;
                    }
                    else if (panose.getSerifStyle() != 0 && info.getPanose().getSerifStyle() != 0)
                    {
                        // mismatch
                        match.score -= 1;
                    }
                    
                    // weight
                    int weight = info.getPanose().getWeight();
                    int weightClass = info.getWeightClassAsPanose();
                    if (Math.abs(weight - weightClass) > 2)
                    {
                        // inconsistent data in system font, usWeightClass wins
                        weight = weightClass;
                    }
                    
                    if (panose.getWeight() == weight)
                    {
                        // exact match
                        match.score += 2;
                    }
                    else if (panose.getWeight() > 1 && weight > 1)
                    {
                        float dist = Math.abs(panose.getWeight() - weight);
                        match.score += 1 - dist * 0.5;
                    }
                    
                    // todo: italic
                    // ...
                }
            }
            else if (fontDescriptor.getFontWeight() > 0 && info.getWeightClass() > 0)
            {
                // usWeightClass is pretty reliable
                float dist = Math.abs(fontDescriptor.getFontWeight() - info.getWeightClass());
                match.score += 1 - (dist / 100) * 0.5;
            }
            // todo: italic
            // ...

            queue.add(match);
        }
        return queue;
    }

    /**
     * Returns true if the character set described by CIDSystemInfo is present in the given font.
     * Only applies to Adobe-GB1, Adobe-CNS1, Adobe-Japan1, Adobe-Korea1, as per the PDF spec.
     */
    private boolean isCharSetMatch(PDCIDSystemInfo cidSystemInfo, FontInfo info)
    {
        if (info.getCIDSystemInfo() != null)
        {
            return info.getCIDSystemInfo().getRegistry().equals(cidSystemInfo.getRegistry()) &&
                   info.getCIDSystemInfo().getOrdering().equals(cidSystemInfo.getOrdering());
        }
        else
        {
            long codePageRange = info.getCodePageRange();
            
            long JIS_JAPAN = 1 << 17;
            long CHINESE_SIMPLIFIED = 1 << 18;
            long KOREAN_WANSUNG = 1 << 19;
            long CHINESE_TRADITIONAL = 1 << 20;
            long KOREAN_JOHAB = 1 << 21;
            
            if (cidSystemInfo.getOrdering().equals("GB1") &&
                    (codePageRange & CHINESE_SIMPLIFIED) == CHINESE_SIMPLIFIED)
            {
                return true;
            }
            else if (cidSystemInfo.getOrdering().equals("CNS1") && 
                    (codePageRange & CHINESE_TRADITIONAL) == CHINESE_TRADITIONAL)
            {
                return true;
            }
            else if (cidSystemInfo.getOrdering().equals("Japan1") &&
                    (codePageRange & JIS_JAPAN) == JIS_JAPAN)
            {
                return true;
            }
            else
            {
                return cidSystemInfo.getOrdering().equals("Korea1") &&
                        (codePageRange & KOREAN_WANSUNG) == KOREAN_WANSUNG ||
                        (codePageRange & KOREAN_JOHAB) == KOREAN_JOHAB;
            }
        }
    }

    /**
     * A potential match for a font substitution.
     */
    private static class FontMatch implements Comparable<FontMatch>
    {
        double score;
        final FontInfo info;
        
        FontMatch(FontInfo info)
        {
            this.info = info;
        }

        @Override
        public int compareTo(FontMatch match)
        {
            return Double.compare(match.score, this.score);
        }
    }

    /**
     * For debugging. Prints all matches and returns the best match.
     */
    private FontMatch printMatches(PriorityQueue<FontMatch> queue)
    {
        FontMatch bestMatch = queue.peek();
        System.out.println("-------");
        while (!queue.isEmpty())
        {
            FontMatch match = queue.poll();
            FontInfo info = match.info;
            System.out.println(match.score + " | " + info.getMacStyle() + " " +
                               info.getFamilyClass() + " " + info.getPanose() + " " +
                               info.getCIDSystemInfo() + " " + info.getPostScriptName() + " " +
                               info.getFormat());
        }
        System.out.println("-------");
        return bestMatch;
    }
}
