/*
 * Copyright (c) 2010 Artem Tikhomirov 
 */
package com.tmate.hgkit.ll;

import static com.tmate.hgkit.ll.HgRepository.TIP;

import java.util.Arrays;

/**
 * Extends Revlog/uses RevlogStream?
 * ? name:HgFileNode?
 * @author artem
 */
public class HgDataFile extends Revlog {

	private final RevlogStream content; // XXX move up to Revlog?

	// absolute from repo root?
	// slashes, unix-style?
	// repo location agnostic, just to give info to user, not to access real storage
	private final String path;
	
	/*package-local*/HgDataFile(HgRepository hgRepo, String path, RevlogStream content) {
		super(hgRepo);
		this.path = path;
		this.content = content;
	}
	
	public boolean exists() {
		return content != null; // XXX need better impl
	}

	public String getPath() {
		return path; // hgRepo.backresolve(this) -> name?
	}

	public int getRevisionCount() {
		return content.revisionCount();
	}

	public byte[] content() {
		return content(TIP);
	}
	
	public byte[] content(int revision) {
		final byte[][] dataPtr = new byte[1][];
		Revlog.Inspector insp = new Revlog.Inspector() {
			public void next(int revisionNumber, int actualLen, int baseRevision, int linkRevision, int parent1Revision, int parent2Revision, byte[] nodeid, byte[] data) {
				dataPtr[0] = data;
			}
		};
		content.iterate(revision, revision, true, insp);
		return dataPtr[0];
	}

	public void history(Changeset.Inspector inspector) {
		if (!exists()) {
			throw new IllegalStateException("Can't get history of invalid repository file node"); 
		}
		final int[] commitRevisions = new int[content.revisionCount()];
		Revlog.Inspector insp = new Revlog.Inspector() {
			int count = 0;
			
			public void next(int revisionNumber, int actualLen, int baseRevision, int linkRevision, int parent1Revision, int parent2Revision, byte[] nodeid, byte[] data) {
				commitRevisions[count++] = linkRevision;
			}
		};
		content.iterate(0, -1, false, insp);
		getRepo().getChangelog().range(inspector, commitRevisions);
	}

	public void history(int start, int end, Changeset.Inspector i) {
		throw HgRepository.notImplemented();
	}

	/**
	 * XXX perhaps, return value Nodeid[2] and boolean needNodeids is better (and higher level) API for this query?
	 * 
	 * @param revision - revision to query parents, or {@link HgRepository#TIP}
	 * @param parentRevisions - int[2] to get local revision numbers of parents (e.g. {6, -1})
	 * @param parent1 - byte[20] or null, if parent's nodeid is not needed
	 * @param parent2 - byte[20] or null, if second parent's nodeid is not needed
	 * @return
	 */
	public void parents(int revision, int[] parentRevisions, byte[] parent1, byte[] parent2) {
		if (revision != TIP && !(revision >= 0 && revision < content.revisionCount())) {
			throw new IllegalArgumentException(String.valueOf(revision));
		}
		if (parentRevisions == null || parentRevisions.length < 2) {
			throw new IllegalArgumentException(String.valueOf(parentRevisions));
		}
		if (parent1 != null && parent1.length < 20) {
			throw new IllegalArgumentException(parent1.toString());
		}
		if (parent2 != null && parent2.length < 20) {
			throw new IllegalArgumentException(parent2.toString());
		}
		class ParentCollector implements Revlog.Inspector {
			public int p1 = -1;
			public int p2 = -1;
			public byte[] nodeid;
			
			public void next(int revisionNumber, int actualLen, int baseRevision, int linkRevision, int parent1Revision, int parent2Revision, byte[] nodeid, byte[] data) {
				p1 = parent1Revision;
				p2 = parent2Revision;
				this.nodeid = new byte[20];
				// nodeid arg now comes in 32 byte from (as in file format description), however upper 12 bytes are zeros.
				System.arraycopy(nodeid, nodeid.length > 20 ? nodeid.length - 20 : 0, this.nodeid, 0, 20);
			}
		};
		ParentCollector pc = new ParentCollector();
		content.iterate(revision, revision, false, pc);
		parentRevisions[0] = pc.p1;
		parentRevisions[1] = pc.p2;
		if (parent1 != null) {
			if (parentRevisions[0] == -1) {
				Arrays.fill(parent1, 0, 20, (byte) 0);
			} else {
				content.iterate(parentRevisions[0], parentRevisions[0], false, pc);
				System.arraycopy(pc.nodeid, 0, parent1, 0, 20);
			}
		}
		if (parent2 != null) {
			if (parentRevisions[1] == -1) {
				Arrays.fill(parent2, 0, 20, (byte) 0);
			} else {
				content.iterate(parentRevisions[1], parentRevisions[1], false, pc);
				System.arraycopy(pc.nodeid, 0, parent2, 0, 20);
			}
		}
	}
}