// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/*
*******************************************************************************
* Copyright (C) 2010-2015, International Business Machines
* Corporation and others.  All Rights Reserved.
*******************************************************************************
* CollationData.java, ported from collationdata.h/.cpp
*
* C++ version created on: 2010oct27
* created by: Markus W. Scherer
*/

package com.ibm.icu.impl.coll;

import com.ibm.icu.impl.Normalizer2Impl;
import com.ibm.icu.impl.Trie2_32;
import com.ibm.icu.lang.UScript;
import com.ibm.icu.text.Collator;
import com.ibm.icu.text.UnicodeSet;
import com.ibm.icu.util.ICUException;

/**
 * Collation data container.
 * Immutable data created by a CollationDataBuilder, or loaded from a file,
 * or deserialized from API-provided binary data.
 *
 * Includes data for the collation base (root/default), aliased if this is not the base.
 */
public final class CollationData {
    // Note: The ucadata.icu loader could discover the reserved ranges by setting an array
    // parallel with the ranges, and resetting ranges that are indexed.
    // The reordering builder code could clone the resulting template array.
    static final int REORDER_RESERVED_BEFORE_LATIN = Collator.ReorderCodes.FIRST + 14;
    static final int REORDER_RESERVED_AFTER_LATIN = Collator.ReorderCodes.FIRST + 15;

    static final int MAX_NUM_SPECIAL_REORDER_CODES = 8;

    CollationData(Normalizer2Impl nfc) {
        nfcImpl = nfc;
    }

    public int getCE32(int c) {
        return trie.get(c);
    }

    int getCE32FromSupplementary(int c) {
        return trie.get(c);  // TODO: port UTRIE2_GET32_FROM_SUPP(trie, c) to Java?
    }

    boolean isDigit(int c) {
        return c < 0x660 ? c <= 0x39 && 0x30 <= c :
                Collation.hasCE32Tag(getCE32(c), Collation.DIGIT_TAG);
    }

    public boolean isUnsafeBackward(int c, boolean numeric) {
        return unsafeBackwardSet.contains(c) || (numeric && isDigit(c));
    }

    public boolean isCompressibleLeadByte(int b) {
        return compressibleBytes[b];
    }

    public boolean isCompressiblePrimary(long p) {
        return isCompressibleLeadByte((int)p >>> 24);
    }

    /**
     * Returns the CE32 from two contexts words.
     * Access to the defaultCE32 for contraction and prefix matching.
     */
    int getCE32FromContexts(int index) {
        return ((int)contexts.charAt(index) << 16) | contexts.charAt(index + 1);
    }

    /**
     * Returns the CE32 for an indirect special CE32 (e.g., with DIGIT_TAG).
     * Requires that ce32 is special.
     */
    int getIndirectCE32(int ce32) {
        assert(Collation.isSpecialCE32(ce32));
        int tag = Collation.tagFromCE32(ce32);
        if(tag == Collation.DIGIT_TAG) {
            // Fetch the non-numeric-collation CE32.
            ce32 = ce32s[Collation.indexFromCE32(ce32)];
        } else if(tag == Collation.LEAD_SURROGATE_TAG) {
            ce32 = Collation.UNASSIGNED_CE32;
        } else if(tag == Collation.U0000_TAG) {
            // Fetch the normal ce32 for U+0000.
            ce32 = ce32s[0];
        }
        return ce32;
    }

    /**
     * Returns the CE32 for an indirect special CE32 (e.g., with DIGIT_TAG),
     * if ce32 is special.
     */
    int getFinalCE32(int ce32) {
        if(Collation.isSpecialCE32(ce32)) {
            ce32 = getIndirectCE32(ce32);
        }
        return ce32;
    }

    /**
     * Computes a CE from c's ce32 which has the OFFSET_TAG.
     */
    long getCEFromOffsetCE32(int c, int ce32) {
        long dataCE = ces[Collation.indexFromCE32(ce32)];
        return Collation.makeCE(Collation.getThreeBytePrimaryForOffsetData(c, dataCE));
    }

    /**
     * Returns the single CE that c maps to.
     * Throws UnsupportedOperationException if c does not map to a single CE.
     */
    long getSingleCE(int c) {
        CollationData d;
        int ce32 = getCE32(c);
        if(ce32 == Collation.FALLBACK_CE32) {
            d = base;
            ce32 = base.getCE32(c);
        } else {
            d = this;
        }
        while(Collation.isSpecialCE32(ce32)) {
            switch(Collation.tagFromCE32(ce32)) {
            case Collation.LATIN_EXPANSION_TAG:
            case Collation.BUILDER_DATA_TAG:
            case Collation.PREFIX_TAG:
            case Collation.CONTRACTION_TAG:
            case Collation.HANGUL_TAG:
            case Collation.LEAD_SURROGATE_TAG:
                throw new UnsupportedOperationException(String.format(
                        "there is not exactly one collation element for U+%04X (CE32 0x%08x)",
                        c, ce32));
            case Collation.FALLBACK_TAG:
            case Collation.RESERVED_TAG_3:
                throw new AssertionError(String.format(
                        "unexpected CE32 tag for U+%04X (CE32 0x%08x)", c, ce32));
            case Collation.LONG_PRIMARY_TAG:
                return Collation.ceFromLongPrimaryCE32(ce32);
            case Collation.LONG_SECONDARY_TAG:
                return Collation.ceFromLongSecondaryCE32(ce32);
            case Collation.EXPANSION32_TAG:
                if(Collation.lengthFromCE32(ce32) == 1) {
                    ce32 = d.ce32s[Collation.indexFromCE32(ce32)];
                    break;
                } else {
                    throw new UnsupportedOperationException(String.format(
                            "there is not exactly one collation element for U+%04X (CE32 0x%08x)",
                            c, ce32));
                }
            case Collation.EXPANSION_TAG: {
                if(Collation.lengthFromCE32(ce32) == 1) {
                    return d.ces[Collation.indexFromCE32(ce32)];
                } else {
                    throw new UnsupportedOperationException(String.format(
                            "there is not exactly one collation element for U+%04X (CE32 0x%08x)",
                            c, ce32));
                }
            }
            case Collation.DIGIT_TAG:
                // Fetch the non-numeric-collation CE32 and continue.
                ce32 = d.ce32s[Collation.indexFromCE32(ce32)];
                break;
            case Collation.U0000_TAG:
                assert(c == 0);
                // Fetch the normal ce32 for U+0000 and continue.
                ce32 = d.ce32s[0];
                break;
            case Collation.OFFSET_TAG:
                return d.getCEFromOffsetCE32(c, ce32);
            case Collation.IMPLICIT_TAG:
                return Collation.unassignedCEFromCodePoint(c);
            }
        }
        return Collation.ceFromSimpleCE32(ce32);
    }

    /**
     * Returns the FCD16 value for code point c. c must be >= 0.
     */
    int getFCD16(int c) {
        return nfcImpl.getFCD16(c);
    }

    /**
     * Returns the first primary for the script's reordering group.
     * @return the primary with only the first primary lead byte of the group
     *         (not necessarily an actual root collator primary weight),
     *         or 0 if the script is unknown
     */
    long getFirstPrimaryForGroup(int script) {
        int index = getScriptIndex(script);
        return index == 0 ? 0 : (long)scriptStarts[index] << 16;
    }

    /**
     * Returns the last primary for the script's reordering group.
     * @return the last primary of the group
     *         (not an actual root collator primary weight),
     *         or 0 if the script is unknown
     */
    public long getLastPrimaryForGroup(int script) {
        int index = getScriptIndex(script);
        if(index == 0) {
            return 0;
        }
        long limit = scriptStarts[index + 1];
        return (limit << 16) - 1;
    }

    /**
     * Finds the reordering group which contains the primary weight.
     * @return the first script of the group, or -1 if the weight is beyond the last group
     */
    public int getGroupForPrimary(long p) {
        p >>= 16;
        if(p < scriptStarts[1] || scriptStarts[scriptStarts.length - 1] <= p) {
            return -1;
        }
        int index = 1;
        while(p >= scriptStarts[index + 1]) { ++index; }
        for(int i = 0; i < numScripts; ++i) {
            if(scriptsIndex[i] == index) {
                return i;
            }
        }
        for(int i = 0; i < MAX_NUM_SPECIAL_REORDER_CODES; ++i) {
            if(scriptsIndex[numScripts + i] == index) {
                return Collator.ReorderCodes.FIRST + i;
            }
        }
        return -1;
    }

    private int getScriptIndex(int script) {
        if(script < 0) {
            return 0;
        } else if(script < numScripts) {
            return scriptsIndex[script];
        } else if(script < Collator.ReorderCodes.FIRST) {
            return 0;
        } else {
            script -= Collator.ReorderCodes.FIRST;
            if(script < MAX_NUM_SPECIAL_REORDER_CODES) {
                return scriptsIndex[numScripts + script];
            } else {
                return 0;
            }
        }
    }

    public int[] getEquivalentScripts(int script) {
        int index = getScriptIndex(script);
        if(index == 0) { return EMPTY_INT_ARRAY; }
        if(script >= Collator.ReorderCodes.FIRST) {
            // Special groups have no aliases.
            return new int[] { script };
        }

        int length = 0;
        for(int i = 0; i < numScripts; ++i) {
            if(scriptsIndex[i] == index) {
                ++length;
            }
        }
        int[] dest = new int[length];
        if(length == 1) {
            dest[0] = script;
            return dest;
        }
        length = 0;
        for(int i = 0; i < numScripts; ++i) {
            if(scriptsIndex[i] == index) {
                dest[length++] = i;
            }
        }
        return dest;
    }

    /**
     * Writes the permutation of primary-weight ranges
     * for the given reordering of scripts and groups.
     * The caller checks for illegal arguments and
     * takes care of [DEFAULT] and memory allocation.
     *
     * <p>Each list element will be a (limit, offset) pair as described
     * for the CollationSettings.reorderRanges.
     * The list will be empty if no ranges are reordered.
     */
    void makeReorderRanges(int[] reorder, UVector32 ranges) {
        makeReorderRanges(reorder, false, ranges);
    }

    private void makeReorderRanges(int[] reorder, boolean latinMustMove, UVector32 ranges) {
        ranges.removeAllElements();
        int length = reorder.length;
        if(length == 0 || (length == 1 && reorder[0] == UScript.UNKNOWN)) {
            return;
        }

        // Maps each script-or-group range to a new lead byte.
        short[] table = new short[scriptStarts.length - 1];  // C++: uint8_t[]

        {
            // Set "don't care" values for reserved ranges.
            int index = scriptsIndex[
                    numScripts + REORDER_RESERVED_BEFORE_LATIN - Collator.ReorderCodes.FIRST];
            if(index != 0) {
                table[index] = 0xff;
            }
            index = scriptsIndex[
                    numScripts + REORDER_RESERVED_AFTER_LATIN - Collator.ReorderCodes.FIRST];
            if(index != 0) {
                table[index] = 0xff;
            }
        }

        // Never reorder special low and high primary lead bytes.
        assert(scriptStarts.length >= 2);
        assert(scriptStarts[0] == 0);
        int lowStart = scriptStarts[1];
        assert(lowStart == ((Collation.MERGE_SEPARATOR_BYTE + 1) << 8));
        int highLimit = scriptStarts[scriptStarts.length - 1];
        assert(highLimit == (Collation.TRAIL_WEIGHT_BYTE << 8));

        // Get the set of special reorder codes in the input list.
        // This supports a fixed number of special reorder codes;
        // it works for data with codes beyond Collator.ReorderCodes.LIMIT.
        int specials = 0;
        for(int i = 0; i < length; ++i) {
            int reorderCode = reorder[i] - Collator.ReorderCodes.FIRST;
            if(0 <= reorderCode && reorderCode < MAX_NUM_SPECIAL_REORDER_CODES) {
                specials |= 1 << reorderCode;
            }
        }

        // Start the reordering with the special low reorder codes that do not occur in the input.
        for(int i = 0; i < MAX_NUM_SPECIAL_REORDER_CODES; ++i) {
            int index = scriptsIndex[numScripts + i];
            if(index != 0 && (specials & (1 << i)) == 0) {
                lowStart = addLowScriptRange(table, index, lowStart);
            }
        }

        // Skip the reserved range before Latin if Latin is the first script,
        // so that we do not move it unnecessarily.
        int skippedReserved = 0;
        if(specials == 0 && reorder[0] == UScript.LATIN && !latinMustMove) {
            int index = scriptsIndex[UScript.LATIN];
            assert(index != 0);
            int start = scriptStarts[index];
            assert(lowStart <= start);
            skippedReserved = start - lowStart;
            lowStart = start;
        }

        // Reorder according to the input scripts, continuing from the bottom of the primary range.
        boolean hasReorderToEnd = false;
        for(int i = 0; i < length;) {
            int script = reorder[i++];
            if(script == UScript.UNKNOWN) {
                // Put the remaining scripts at the top.
                hasReorderToEnd = true;
                while(i < length) {
                    script = reorder[--length];
                    if(script == UScript.UNKNOWN) {  // Must occur at most once.
                        throw new IllegalArgumentException(
                                "setReorderCodes(): duplicate UScript.UNKNOWN");
                    }
                    if(script == Collator.ReorderCodes.DEFAULT) {
                        throw new IllegalArgumentException(
                                "setReorderCodes(): UScript.DEFAULT together with other scripts");
                    }
                    int index = getScriptIndex(script);
                    if(index == 0) { continue; }
                    if(table[index] != 0) {  // Duplicate or equivalent script.
                        throw new IllegalArgumentException(
                                "setReorderCodes(): duplicate or equivalent script " +
                                scriptCodeString(script));
                    }
                    highLimit = addHighScriptRange(table, index, highLimit);
                }
                break;
            }
            if(script == Collator.ReorderCodes.DEFAULT) {
                // The default code must be the only one in the list, and that is handled by the caller.
                // Otherwise it must not be used.
                throw new IllegalArgumentException(
                        "setReorderCodes(): UScript.DEFAULT together with other scripts");
            }
            int index = getScriptIndex(script);
            if(index == 0) { continue; }
            if(table[index] != 0) {  // Duplicate or equivalent script.
                throw new IllegalArgumentException(
                        "setReorderCodes(): duplicate or equivalent script " +
                        scriptCodeString(script));
            }
            lowStart = addLowScriptRange(table, index, lowStart);
        }

        // Put all remaining scripts into the middle.
        for(int i = 1; i < scriptStarts.length - 1; ++i) {
            int leadByte = table[i];
            if(leadByte != 0) { continue; }
            int start = scriptStarts[i];
            if(!hasReorderToEnd && start > lowStart) {
                // No need to move this script.
                lowStart = start;
            }
            lowStart = addLowScriptRange(table, i, lowStart);
        }
        if(lowStart > highLimit) {
            if((lowStart - (skippedReserved & 0xff00)) <= highLimit) {
                // Try not skipping the before-Latin reserved range.
                makeReorderRanges(reorder, true, ranges);
                return;
            }
            // We need more primary lead bytes than available, despite the reserved ranges.
            throw new ICUException(
                    "setReorderCodes(): reordering too many partial-primary-lead-byte scripts");
        }

        // Turn lead bytes into a list of (limit, offset) pairs.
        // Encode each pair in one list element:
        // Upper 16 bits = limit, lower 16 = signed lead byte offset.
        int offset = 0;
        for(int i = 1;; ++i) {
            int nextOffset = offset;
            while(i < scriptStarts.length - 1) {
                int newLeadByte = table[i];
                if(newLeadByte == 0xff) {
                    // "Don't care" lead byte for reserved range, continue with current offset.
                } else {
                    nextOffset = newLeadByte - (scriptStarts[i] >> 8);
                    if(nextOffset != offset) { break; }
                }
                ++i;
            }
            if(offset != 0 || i < scriptStarts.length - 1) {
                ranges.addElement(((int)scriptStarts[i] << 16) | (offset & 0xffff));
            }
            if(i == scriptStarts.length - 1) { break; }
            offset = nextOffset;
        }
    }

    private int addLowScriptRange(short[] table, int index, int lowStart) {
        int start = scriptStarts[index];
        if((start & 0xff) < (lowStart & 0xff)) {
            lowStart += 0x100;
        }
        table[index] = (short)(lowStart >> 8);
        int limit = scriptStarts[index + 1];
        lowStart = ((lowStart & 0xff00) + ((limit & 0xff00) - (start & 0xff00))) | (limit & 0xff);
        return lowStart;
    }

    private int addHighScriptRange(short[] table, int index, int highLimit) {
        int limit = scriptStarts[index + 1];
        if((limit & 0xff) > (highLimit & 0xff)) {
            highLimit -= 0x100;
        }
        int start = scriptStarts[index];
        highLimit = ((highLimit & 0xff00) - ((limit & 0xff00) - (start & 0xff00))) | (start & 0xff);
        table[index] = (short)(highLimit >> 8);
        return highLimit;
    }

    private static String scriptCodeString(int script) {
        // Do not use the script name here: We do not want to depend on that data.
        return (script < Collator.ReorderCodes.FIRST) ?
                Integer.toString(script) : "0x" + Integer.toHexString(script);
    }

    private static final int[] EMPTY_INT_ARRAY = new int[0];

    /** @see jamoCE32s */
    static final int JAMO_CE32S_LENGTH = 19 + 21 + 27;

    /** Main lookup trie. */
    Trie2_32 trie;
    /**
     * Array of CE32 values.
     * At index 0 there must be CE32(U+0000)
     * to support U+0000's special-tag for NUL-termination handling.
     */
    int[] ce32s;
    /** Array of CE values for expansions and OFFSET_TAG. */
    long[] ces;
    /** Array of prefix and contraction-suffix matching data. */
    String contexts;
    /** Base collation data, or null if this data itself is a base. */
    public CollationData base;
    /**
     * Simple array of JAMO_CE32S_LENGTH=19+21+27 CE32s, one per canonical Jamo L/V/T.
     * They are normally simple CE32s, rarely expansions.
     * For fast handling of HANGUL_TAG.
     */
    int[] jamoCE32s = new int[JAMO_CE32S_LENGTH];
    public Normalizer2Impl nfcImpl;
    /** The single-byte primary weight (xx000000) for numeric collation. */
    long numericPrimary = 0x12000000;

    /** 256 flags for which primary-weight lead bytes are compressible. */
    public boolean[] compressibleBytes;
    /**
     * Set of code points that are unsafe for starting string comparison after an identical prefix,
     * or in backwards CE iteration.
     */
    UnicodeSet unsafeBackwardSet;

    /**
     * Fast Latin table for common-Latin-text string comparisons.
     * Data structure see class CollationFastLatin.
     */
    public char[] fastLatinTable;
    /**
     * Header portion of the fastLatinTable.
     * In C++, these are one array, and the header is skipped for mapping characters.
     * In Java, two arrays work better.
     */
    char[] fastLatinTableHeader;

    /**
     * Data for scripts and reordering groups.
     * Uses include building a reordering permutation table and
     * providing script boundaries to AlphabeticIndex.
     */
    int numScripts;
    /**
     * The length of scriptsIndex is numScripts+16.
     * It maps from a UScriptCode or a special reorder code to an entry in scriptStarts.
     * 16 special reorder codes (not all used) are mapped starting at numScripts.
     * Up to MAX_NUM_SPECIAL_REORDER_CODES are codes for special groups like space/punct/digit.
     * There are special codes at the end for reorder-reserved primary ranges.
     *
     * <p>Multiple scripts may share a range and index, for example Hira & Kana.
     */
    char[] scriptsIndex;
    /**
     * Start primary weight (top 16 bits only) for a group/script/reserved range
     * indexed by scriptsIndex.
     * The first range (separators & terminators) and the last range (trailing weights)
     * are not reorderable, and no scriptsIndex entry points to them.
     */
    char[] scriptStarts;

    /**
     * Collation elements in the root collator.
     * Used by the CollationRootElements class. The data structure is described there.
     * null in a tailoring.
     */
    public long[] rootElements;
}