/src/main/java/com/atlassian/jira/plugins/bitbucket/spi/github/impl/GithubChangesetIterator.java

package com.atlassian.jira.plugins.bitbucket.spi.github.impl;



import com.atlassian.jira.plugins.bitbucket.api.Changeset;

import com.atlassian.jira.plugins.bitbucket.api.SourceControlRepository;



import java.util.Collections;

import java.util.Iterator;

import java.util.List;

import java.util.ListIterator;

import java.util.NoSuchElementException;



public class GithubChangesetIterator implements Iterator<Changeset>

{

    private ListIterator<Changeset> inPageChangesetsIterator = Collections.<Changeset>emptyList().listIterator();

    private PagesIterator pagesIterator;



    private BranchesIterator branchesIterator;





    public GithubChangesetIterator(GithubCommunicator githubCommunicator, SourceControlRepository repository, List<String> branches)

    {

        branchesIterator = new BranchesIterator(branches, githubCommunicator, repository);

        pagesIterator = branchesIterator.next();

    }



    public boolean hasNext()

    {

        return inPageChangesetsIterator.hasNext() || (pagesIterator != null && pagesIterator.hasNext()) || branchesIterator.hasNext() ;

    }



    public Changeset next()

    {

        if (inPageChangesetsIterator.hasNext())

        {

            return inPageChangesetsIterator.next();

        } else if (pagesIterator.hasNext())

        {

            inPageChangesetsIterator = pagesIterator.next();

            return next();

        } else if (branchesIterator.hasNext()) {

            pagesIterator = branchesIterator.next();

            return next();

        }



        throw new NoSuchElementException();

    }



    public void remove()

    {

        throw new UnsupportedOperationException();

    }

}



class PagesIterator implements Iterator<ListIterator<Changeset>>

{



    private GithubCommunicator githubCommunicator;

    private SourceControlRepository repository;



    private int index = 0;

    private int currentPageNumber = 0;   // github gives us pages indexed from 1 (zero is one before)

    private String branch;

    private List<Changeset> changesets;



    PagesIterator(String branch, GithubCommunicator githubCommunicator, SourceControlRepository repository)

    {

        this.branch = branch;

        this.githubCommunicator = githubCommunicator;

        this.repository = repository;

    }



    @Override

    public boolean hasNext()

    {

        if (index < currentPageNumber) {

            return containsChangesets();

        }

        currentPageNumber++;

        changesets = githubCommunicator.getChangesets(repository, branch, currentPageNumber);

        return containsChangesets();



    }



    private boolean containsChangesets() {

        return changesets != null && !changesets.isEmpty();

    }



    @Override

    public ListIterator<Changeset> next()

    {

        index++;

        if (index != currentPageNumber && !hasNext()) {

            throw new NoSuchElementException();

        }

        if (changesets != null && !changesets.isEmpty()) {

            return changesets.listIterator();

        }

        return Collections.<Changeset>emptyList().listIterator();

    }



    @Override

    public void remove()

    {

        throw new UnsupportedOperationException();

    }

}



class BranchesIterator implements Iterator<PagesIterator>

{





    private ListIterator<String> branchNamesIterator = Collections.<String>emptyList().listIterator();

    private GithubCommunicator githubCommunicator;

    private SourceControlRepository repository;



    BranchesIterator(List<String> branches, GithubCommunicator githubCommunicator, SourceControlRepository repository)

    {

        this.githubCommunicator = githubCommunicator;

        this.repository = repository;

        this.branchNamesIterator = branches.listIterator();

    }



    @Override

    public boolean hasNext()

    {

        return branchNamesIterator.hasNext();

    }



    @Override

    public PagesIterator next()

    {

        if (!hasNext())

        {

            return null;

        }



        return new PagesIterator(branchNamesIterator.next(), githubCommunicator, repository);

    }



    @Override

    public void remove()

    {

        throw new UnsupportedOperationException();

    }

}