package org.unicode.cldr.draft;

import java.text.FieldPosition;
import java.text.Format;
import java.text.ParsePosition;
import java.util.BitSet;
import java.util.Set;
import java.util.TreeSet;

import org.unicode.cldr.draft.PatternFixer.Target;

import com.ibm.icu.impl.Utility;
import com.ibm.icu.lang.UCharacter;
import com.ibm.icu.lang.UProperty;
import com.ibm.icu.text.UTF16;
import com.ibm.icu.text.UnicodeSet;
import com.ibm.icu.text.UnicodeSetIterator;

public class UnicodeSetFormat extends Format {

    public UnicodeSetFormat(Target target) {
        this.target = target;
    }

    public UnicodeSetFormat(Target target, int patternOptions) {
        this.target = target;
        this.options = patternOptions;
    }

    // main methods

    @Override
    // TODO clean up prototype
    public StringBuffer format(Object obj, StringBuffer toAppendTo, FieldPosition pos) {
        // API for Format calls for StringBuffer, but should update to StringBuilder
        int startPos = toAppendTo.length();
        Set<String> strings = null;
        toAppendTo.append('[');
        for (UnicodeSetIterator it = new UnicodeSetIterator((UnicodeSet) obj); it.nextRange();) {
            if (it.codepoint == UnicodeSetIterator.IS_STRING) {
                if (strings == null) {
                    strings = new TreeSet<String>();
                }
                strings.add(it.string);
                continue;
            }
            appendQuoted(toAppendTo, it.codepoint);
            if (it.codepointEnd != it.codepoint) {
                appendQuoted(toAppendTo.append('-'), it.codepointEnd);
            }
        }
        toAppendTo.append(']');
        if (strings != null) { // edge case
            StringBuffer extras = new StringBuffer("(?:");
            for (String string : strings) {
                appendQuoted(extras, string).append('|');
            }
            toAppendTo.insert(startPos, extras);
            toAppendTo.append(')');
        }
        return toAppendTo;
    }

    // TODO optimize this to only quote what is needed for the particular target
    // and (possibly) the given location in the character class
    private StringBuffer appendQuoted(StringBuffer target, int codePoint) {
        switch (codePoint) {
        case '[': // SET_OPEN:
        case ']': // SET_CLOSE:
        case '-': // HYPHEN:
        case '^': // COMPLEMENT:
        case '&': // INTERSECTION:
        case '\\': // BACKSLASH:
        case '{':
        case '}':
        case '$':
        case ':':
            target.append('\\');
            break;
        default:
            if (toQuote.contains(codePoint)) {
                if (codePoint > 0xFFFF) {
                    target.append("\\u");
                    target.append(Utility.hex(UTF16.getLeadSurrogate(codePoint), 4));
                    codePoint = UTF16.getTrailSurrogate(codePoint);
                }
                target.append("\\u");
                target.append(Utility.hex(codePoint, 4));
                return target;
            }
        }
        UTF16.append(target, codePoint);
        return target;
    }

    private StringBuffer appendQuoted(StringBuffer target, String string) {
        for (int i = 0; i < string.length(); ++i) {
            appendQuoted(target, string.charAt(i));
            // don't worry about surrogates; this works in Java
            // for other Targets we may have to fix.
        }
        return target;
    }

    @Override
    public final UnicodeSet parseObject(String pattern, ParsePosition pos) {
        return new UnicodeSet(pattern, pos, null);
    }

    // settings

    public Target getTarget() {
        return target;
    }

    public UnicodeSetFormat setTarget(Target target) {
        this.target = target;
        return this;
    }

    public int getOptions() {
        return options;
    }

    public UnicodeSetFormat setOptions(int options) {
        this.options = options;
        return this;
    }

    public Extension[] getExtensions() {
        return extensions;
    }

    public UnicodeSetFormat setExtensions(Extension... extensions) {
        this.extensions = extensions;
        return this;
    }

    public abstract class Extension {

        /**
         * Is called every time an unquoted $ is found. Should parse out variables as appropriate
         * and return how far we got, and the replacement string. Returns null if doesn't match a variable.
         * 
         * @pos on input should be set to the position just before the dollar sign.
         *      On output should be set to the end of the text to replace.
         */
        public abstract String replaceVariable(String pattern, ParsePosition pos);

        /**
         * Resolves anything that looks like a property, eg: <br>
         * encountering \p{whitespace} or [:whitespace:] would call
         * getProperty("whitespace", "", false, result)<br>
         * while
         * \p{bidi_class=neutral} would call getProperty("bidi_class", "neutral",
         * false, result) and <br>
         * \p{name=/DOT/} would call
         * getProperty("bidi_class", "neutral", false, result) <br>
         * (for an example of the latter, see {@linkplain http
         * ://unicode.org/cldr/utility/list-unicodeset.jsp?a=\p name=/WITH%20DOT%20ABOVE/}
         * 
         * @param regex
         *            Set to true if the property value is a regex "find" expression. In that case,
         *            the return value should be the set of Unicode characters that match the regex.
         */
        public abstract boolean getProperty(String propertyName, String propertyValue, boolean regex, UnicodeSet result);

    }

    public String formatWithProperties(UnicodeSet original, boolean addOthers, UnicodeSet expandBlockIgnorables,
        int... properties) {
        UnicodeSet remainder = new UnicodeSet().addAll(original);
        Set<String> propSet = new TreeSet<String>();
        BitSet props = new BitSet();

        for (int i = 0; i < properties.length; ++i) {
            reduceByProperty(original, expandBlockIgnorables, properties[i], remainder, propSet);
            props.set(i);
        }
        if (addOthers) {
            for (int i = UProperty.INT_START; i < UProperty.INT_LIMIT; ++i) {
                if (props.get(i)) continue;
                reduceByProperty(original, expandBlockIgnorables, i, remainder, propSet);
            }
        }
        StringBuffer result = new StringBuffer("[ ");
        for (String prop : propSet) {
            result.append(prop).append(" ");
        }
        if (expandBlockIgnorables != null) {
            result.append("- ").append(expandBlockIgnorables.toPattern(true));
        }
        if (remainder.size() > 0) {
            result.append(" ").append(remainder.toPattern(true));
        }
        result.append("]");
        return result.toString();
    }

    static final int blockEnum = UCharacter.getPropertyEnum("block");

    private void reduceByProperty(UnicodeSet original, UnicodeSet expandBlockIgnorables, int property,
        UnicodeSet remainder, Set<String> result) {
        String propertyAlias = UCharacter.getPropertyName(property, UProperty.NameChoice.SHORT);
        UnicodeSet valueChars = new UnicodeSet();
        for (int i = UCharacter.getIntPropertyMinValue(property); i <= UCharacter.getIntPropertyMaxValue(property); ++i) {
            String valueAlias = UCharacter.getPropertyValueName(property, i, UProperty.NameChoice.SHORT);
            if (valueAlias == null) {
                valueAlias = UCharacter.getPropertyValueName(property, i, UProperty.NameChoice.LONG);
            }
            if (valueAlias == null) continue;

            valueChars.clear();
            valueChars.applyPropertyAlias(propertyAlias, valueAlias);
            if (remainder.containsSome(valueChars)) {
                if (original.containsAll(valueChars)) {
                    result.add("[:" + propertyAlias + '=' + valueAlias + ":]");
                    remainder.removeAll(valueChars);
                } else if (property == blockEnum && expandBlockIgnorables != null) {
                    UnicodeSet hasScript = new UnicodeSet(valueChars).removeAll(expandBlockIgnorables);
                    if (hasScript.size() > 5 && original.containsAll(hasScript)) {
                        System.out.println("Broadening to block: " + valueAlias);
                        result.add("[:" + propertyAlias + '=' + valueAlias + ":]");
                        remainder.removeAll(valueChars);
                    }
                }
            }
        }
    }

    // ===== PRIVATES =====
    private static final long serialVersionUID = 1L;
    private Target target;
    private int options;
    private Extension[] extensions;
    private static final UnicodeSet toQuote = (UnicodeSet) new UnicodeSet(
        "[[:Cn:][:Default_Ignorable_Code_Point:][:patternwhitespace:]]").freeze();

}