package aarddict; 

 

import java.io.IOException; 

import java.util.HashMap; 

import java.util.Map; 

import java.util.UUID; 

 

public final class Header { 

 

    public final String signature; 

    public final String sha1sum; 

    public final UUID   uuid; 

    public final int    version; 

    public final int    volume; 

    public final int    of; 

    public final long   metaLength; 

    public final long   indexCount; 

    public final long   articleOffset; 

    public final String index1ItemFormat; 

    public final String keyLengthFormat; 

    public final String articleLengthFormat; 

    public final long   index1Offset; 

    public final long   index2Offset; 

    public final int    index1ItemSize; 

    public final char   keyPointerSpec; 

    public final char   articlePointerSpec; 

    public final char   keyLengthSpec; 

    public final char   articleLengthSpec; 

 

    Header(RandomAccessFile file) throws IOException { 

        int specLen = 0; 

        this.signature = file.readUTF8(4); 

        specLen += 4; 

 

        this.sha1sum = file.readUTF8(40); 

        specLen += 40; 

 

        this.version = file.readUnsignedShort(); 

        specLen += 2; 

 

        this.uuid = file.readUUID(); 

        specLen += 16; 

 

        this.volume = file.readUnsignedShort(); 

        specLen += 2; 

 

        this.of = file.readUnsignedShort(); 

        specLen += 2; 

 

        this.metaLength = file.readUnsignedInt(); 

        specLen += 4; 

 

        this.indexCount = file.readUnsignedInt(); 

        specLen += 4; 

 

        this.articleOffset = file.readUnsignedInt(); 

        specLen += 4; 

 

        this.index1ItemFormat = file.readUTF8(4); 

        specLen += 4; 

 

        this.keyLengthFormat = file.readUTF8(2); 

        specLen += 2; 

        this.keyLengthSpec = this.keyLengthFormat.charAt(1); 

 

        this.articleLengthFormat = file.readUTF8(2); 

        specLen += 2; 

        this.articleLengthSpec = this.articleLengthFormat.charAt(1); 

         

        this.index1ItemSize = calcSize(this.index1ItemFormat); 

         

        this.index1Offset = specLen + this.metaLength; 

        this.index2Offset = this.index1Offset + this.indexCount*this.index1ItemSize; 

        this.keyPointerSpec = this.index1ItemFormat.charAt(1); 

        this.articlePointerSpec = this.index1ItemFormat.charAt(2); 

    } 

     

    static Map<Character, Integer> structSizes = new HashMap<Character, Integer>() { 

                                                   { 

                                                       put('h', 2); 

                                                       put('H', 2); 

                                                       put('i', 4); 

                                                       put('I', 4); 

                                                       put('l', 4); 

                                                       put('L', 4); 

                                                       put('q', 8); 

                                                       put('Q', 8); 

                                                   } 

                                               }; 

     

    static int calcSize(String structSpec) { 

        int size = 0; 

        int length = structSpec.length(); 

        //ignore byte order spec at index 0 

        for (int i = 1; i < length; i++) { 

            char c = structSpec.charAt(i); 

            Integer unitSize = structSizes.get(c); 

            if (unitSize != null) { 

                size += unitSize; 

            } 

        } 

        return size; 

    }