import nimgit2
import types, free, oid

proc walk* (repo: GitRepository): GitRevisionWalker =
    let error = git_revwalk_new(addr result, repo)

    if error != 0:
        free(result)
        raise newException(CatchableError, "Cannot create RevWalker: " & $error.getResultCode)


proc sort* (walker: GitRevisionWalker, sort: git_sort_t = GIT_SORT_TOPOLOGICAL) = 
    let error = git_revwalk_sorting(walker, cast[cuint](sort))

    if error != 0:
        free(walker)
        raise newException(CatchableError, "Cannot set sorting: " & $error.getResultCode)


proc push* (walker: GitRevisionWalker, reference: string) =
    let error = git_revwalk_push_ref(walker, cstring(reference))

    if error != 0:
        free(walker)
        raise newException(CatchableError, "Cannot push reference: " & $error.getResultCode)

proc push* (walker: GitRevisionWalker, objectId: GitObjectId) =
    let error = git_revwalk_push(walker, objectId)

    if error != 0:
        free(walker)
        raise newException(CatchableError, "Cannot push objectId: " & $error.getResultCode)

proc pushHead* (walker: GitRevisionWalker) =
    let error = git_revwalk_push_head(walker)

    if error != 0:
        free(walker)
        raise newException(CatchableError, "Cannot push head: " & $error.getResultCode)


proc hide* (walker: GitRevisionWalker, objectId: GitObjectId) =
    let error = git_revwalk_hide(walker, objectId)

    if error != 0:
        free(walker)
        raise newException(CatchableError, "Cannot push objectId: " & $error.getResultCode)

proc hideHead* (walker: GitRevisionWalker) =
    let error = git_revwalk_hide_head(walker)

    if error != 0:
        free(walker)
        raise newException(CatchableError, "Cannot push head: " & $error.getResultCode)


proc simplifyFirstParent* (walker: GitRevisionWalker) =
    let error = git_revwalk_simplify_first_parent(walker)

    if error != 0:
        free(walker)
        raise newException(CatchableError, "Cannot simplify walker: " & $error.getResultCode)

proc reset* (walker: GitRevisionWalker) = 
    let error = git_revwalk_reset(walker)

    if error != 0:
        free(walker)
        raise newException(CatchableError, "Cannot simplify walker: " & $error.getResultCode)


iterator items* (walker: GitRevisionWalker): GitObjectId =
    var
      objectId = initGitObjectId()

    while true:
        let code = git_revwalk_next(objectId, walker).getResultCode
        case code:
            of grcOk:
                yield objectId

            of grcIterOver:
                free(walker)
                break

            else:
                raise newException(CatchableError, "iteration error: " & $code)