/*
 * 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.maven.repository.metadata;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.TreeSet;

import org.apache.maven.artifact.ArtifactScopeEnum;

/**
 * maven dependency metadata graph
 *
 * @author <a href="oleg@codehaus.org">Oleg Gusakov</a>
 *
 */
public class MetadataGraph {
    public static final int DEFAULT_VERTICES = 32;
    public static final int DEFAULT_EDGES = 64;

    // flags to indicate the granularity of vertices
    private boolean versionedVertices = false;
    private boolean scopedVertices = false;
    /**
     * the entry point we started building the graph from
     */
    MetadataGraphVertex entry;

    // graph vertices
    TreeSet<MetadataGraphVertex> vertices;

    /**
     * incident and excident edges per node
     */
    Map<MetadataGraphVertex, List<MetadataGraphEdge>> incidentEdges;

    Map<MetadataGraphVertex, List<MetadataGraphEdge>> excidentEdges;

    /**
     *  null in dirty graph, actual
     *  scope for conflict-resolved graph
     */
    ArtifactScopeEnum scope;

    // ------------------------------------------------------------------------
    /**
     * init graph
     */
    public MetadataGraph(int nVertices) {
        init(nVertices, 2 * nVertices);
    }

    public MetadataGraph(int nVertices, int nEdges) {
        init(nVertices, nEdges);
    }
    // ------------------------------------------------------------------------
    /**
     * construct a single vertex
     */
    public MetadataGraph(MetadataGraphVertex entry) throws MetadataResolutionException {
        checkVertex(entry);
        checkVertices(1);

        entry.setCompareVersion(versionedVertices);
        entry.setCompareScope(scopedVertices);

        vertices.add(entry);
        this.entry = entry;
    }
    // ------------------------------------------------------------------------
    /**
     * construct graph from a "dirty" tree
     */
    public MetadataGraph(MetadataTreeNode tree) throws MetadataResolutionException {
        this(tree, false, false);
    }
    // ------------------------------------------------------------------------
    /**
     * construct graph from a "dirty" tree
     *
     * @param tree "dirty" tree root
     * @param versionedVertices true if graph nodes should be versioned (different versions -&gt; different nodes)
     * @param scopedVertices true if graph nodes should be versioned and scoped
     * (different versions and/or scopes -&gt; different nodes)
     *
     */
    public MetadataGraph(MetadataTreeNode tree, boolean versionedVertices, boolean scopedVertices)
            throws MetadataResolutionException {
        if (tree == null) {
            throw new MetadataResolutionException("tree is null");
        }

        setVersionedVertices(versionedVertices);
        setScopedVertices(scopedVertices);

        this.versionedVertices = scopedVertices || versionedVertices;
        this.scopedVertices = scopedVertices;

        int count = countNodes(tree);

        init(count, count + (count / 2));

        processTreeNodes(null, tree, 0, 0);
    }
    // ------------------------------------------------------------------------
    private void processTreeNodes(MetadataGraphVertex parentVertex, MetadataTreeNode node, int depth, int pomOrder)
            throws MetadataResolutionException {
        if (node == null) {
            return;
        }

        MetadataGraphVertex vertex = new MetadataGraphVertex(node.md, versionedVertices, scopedVertices);
        if (!vertices.contains(vertex)) {
            vertices.add(vertex);
        }

        if (parentVertex != null) // then create the edge
        {
            ArtifactMetadata md = node.getMd();
            MetadataGraphEdge e =
                    new MetadataGraphEdge(md.version, md.resolved, md.artifactScope, md.artifactUri, depth, pomOrder);
            addEdge(parentVertex, vertex, e);
        } else {
            entry = vertex;
        }

        MetadataTreeNode[] kids = node.getChildren();
        if (kids == null || kids.length < 1) {
            return;
        }

        for (int i = 0; i < kids.length; i++) {
            MetadataTreeNode n = kids[i];
            processTreeNodes(vertex, n, depth + 1, i);
        }
    }
    // ------------------------------------------------------------------------
    public MetadataGraphVertex findVertex(ArtifactMetadata md) {
        if (md == null || vertices == null || vertices.size() < 1) {
            return null;
        }

        MetadataGraphVertex v = new MetadataGraphVertex(md);
        v.setCompareVersion(versionedVertices);
        v.setCompareScope(scopedVertices);

        for (MetadataGraphVertex gv : vertices) {
            if (gv.equals(v)) {
                return gv;
            }
        }

        return null;
    }
    // ------------------------------------------------------------------------
    public MetadataGraphVertex addVertex(ArtifactMetadata md) {
        if (md == null) {
            return null;
        }

        checkVertices();

        MetadataGraphVertex v = findVertex(md);
        if (v != null) {
            return v;
        }

        v = new MetadataGraphVertex(md);

        v.setCompareVersion(versionedVertices);
        v.setCompareScope(scopedVertices);

        vertices.add(v);
        return v;
    }
    // ------------------------------------------------------------------------
    /**
     * init graph
     */
    private void init(int nVertices, int nEdges) {
        int nV = nVertices;
        if (nVertices < 1) {
            nV = 1;
        }

        checkVertices(nV);

        int nE = nVertices;
        if (nEdges <= nV) {
            nE = 2 * nE;
        }

        checkEdges(nE);
    }

    private void checkVertices() {
        checkVertices(DEFAULT_VERTICES);
    }

    private void checkVertices(int nVertices) {
        if (vertices == null) {
            vertices = new TreeSet<>();
        }
    }

    private void checkEdges() {
        int count = DEFAULT_EDGES;

        if (vertices != null) {
            count = vertices.size() + vertices.size() / 2;
        }

        checkEdges(count);
    }

    private void checkEdges(int nEdges) {
        if (incidentEdges == null) {
            incidentEdges = new HashMap<>(nEdges);
        }
        if (excidentEdges == null) {
            excidentEdges = new HashMap<>(nEdges);
        }
    }
    // ------------------------------------------------------------------------
    private static void checkVertex(MetadataGraphVertex v) throws MetadataResolutionException {
        if (v == null) {
            throw new MetadataResolutionException("null vertex");
        }
        if (v.getMd() == null) {
            throw new MetadataResolutionException("vertex without metadata");
        }
    }
    // ------------------------------------------------------------------------
    private static void checkEdge(MetadataGraphEdge e) throws MetadataResolutionException {
        if (e == null) {
            throw new MetadataResolutionException("badly formed edge");
        }
    }
    // ------------------------------------------------------------------------
    public List<MetadataGraphEdge> getEdgesBetween(MetadataGraphVertex vFrom, MetadataGraphVertex vTo) {
        List<MetadataGraphEdge> edges = getIncidentEdges(vTo);
        if (edges == null || edges.isEmpty()) {
            return null;
        }

        List<MetadataGraphEdge> res = new ArrayList<>(edges.size());

        for (MetadataGraphEdge e : edges) {
            if (e.getSource().equals(vFrom)) {
                res.add(e);
            }
        }

        return res;
    }
    // ------------------------------------------------------------------------
    public MetadataGraph addEdge(MetadataGraphVertex vFrom, MetadataGraphVertex vTo, MetadataGraphEdge e)
            throws MetadataResolutionException {
        checkVertex(vFrom);
        checkVertex(vTo);

        checkVertices();

        checkEdge(e);
        checkEdges();

        e.setSource(vFrom);
        e.setTarget(vTo);

        vFrom.setCompareVersion(versionedVertices);
        vFrom.setCompareScope(scopedVertices);

        List<MetadataGraphEdge> exList = excidentEdges.get(vFrom);
        if (exList == null) {
            exList = new ArrayList<>();
            excidentEdges.put(vFrom, exList);
        }

        if (!exList.contains(e)) {
            exList.add(e);
        }

        List<MetadataGraphEdge> inList = incidentEdges.get(vTo);
        if (inList == null) {
            inList = new ArrayList<>();
            incidentEdges.put(vTo, inList);
        }

        if (!inList.contains(e)) {
            inList.add(e);
        }

        return this;
    }
    // ------------------------------------------------------------------------
    public MetadataGraph removeVertex(MetadataGraphVertex v) {
        if (vertices != null && v != null) {
            vertices.remove(v);
        }

        if (incidentEdges != null) {
            incidentEdges.remove(v);
        }

        if (excidentEdges != null) {
            excidentEdges.remove(v);
        }

        return this;
    }
    // ------------------------------------------------------------------------
    private static int countNodes(MetadataTreeNode tree) {
        if (tree == null) {
            return 0;
        }

        int count = 1;
        MetadataTreeNode[] kids = tree.getChildren();
        if (kids == null || kids.length < 1) {
            return count;
        }
        for (MetadataTreeNode n : kids) {
            count += countNodes(n);
        }

        return count;
    }

    // ------------------------------------------------------------------------
    public MetadataGraphVertex getEntry() {
        return entry;
    }

    public void setEntry(MetadataGraphVertex entry) {
        this.entry = entry;
    }

    public TreeSet<MetadataGraphVertex> getVertices() {
        return vertices;
    }

    public List<MetadataGraphEdge> getIncidentEdges(MetadataGraphVertex vertex) {
        checkEdges();
        return incidentEdges.get(vertex);
    }

    public List<MetadataGraphEdge> getExcidentEdges(MetadataGraphVertex vertex) {
        checkEdges();
        return excidentEdges.get(vertex);
    }

    public boolean isVersionedVertices() {
        return versionedVertices;
    }

    public void setVersionedVertices(boolean versionedVertices) {
        this.versionedVertices = versionedVertices;
    }

    public boolean isScopedVertices() {
        return scopedVertices;
    }

    public void setScopedVertices(boolean scopedVertices) {
        this.scopedVertices = scopedVertices;

        // scoped graph is versioned by definition
        if (scopedVertices) {
            versionedVertices = true;
        }
    }

    public ArtifactScopeEnum getScope() {
        return scope;
    }

    public void setScope(ArtifactScopeEnum scope) {
        this.scope = scope;
    }

    // ------------------------------------------------------------------------
    public boolean isEmpty() {
        return entry == null || vertices == null || vertices.isEmpty();
    }

    // ------------------------------------------------------------------------
    public boolean isEmptyEdges() {
        return isEmpty() || incidentEdges == null || incidentEdges.isEmpty();
    }
    // ------------------------------------------------------------------------
    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder(512);
        if (isEmpty()) {
            return "empty";
        }
        for (MetadataGraphVertex v : vertices) {
            sb.append("Vertex:  ").append(v.getMd().toString()).append('\n');
            List<MetadataGraphEdge> ins = getIncidentEdges(v);
            if (ins != null) {
                for (MetadataGraphEdge e : ins) {
                    sb.append("       from :  ").append(e.toString()).append('\n');
                }
            } else {
                sb.append("      no entries\n");
            }

            List<MetadataGraphEdge> outs = getExcidentEdges(v);
            if (outs != null) {
                for (MetadataGraphEdge e : outs) {
                    sb.append("        to :  ").append(e.toString()).append('\n');
                }
            } else {
                sb.append("      no exit\n");
            }

            sb.append("-------------------------------------------------\n");
        }
        sb.append("=============================================================\n");
        return sb.toString();
    }

    // ------------------------------------------------------------------------
    // ------------------------------------------------------------------------
}
