-module(gleamy@structures@priority_queue).
-compile([no_auto_import, nowarn_unused_vars]).

-export([is_empty/1, new/1, from_list/2, pop/1, peek/1, push/2, count/1, reorder/2, to_list/1]).

-spec is_empty(gleamy@structures@heap@pairing_heap:heap(any())) -> boolean().
is_empty(Queue) ->
    case gleamy@structures@heap@pairing_heap:find_min(Queue) of
        {ok, _} ->
            false;

        {error, _} ->
            true
    end.

-spec new(fun((GQE, GQE) -> gleam@order:order())) -> gleamy@structures@heap@pairing_heap:heap(GQE).
new(Compare) ->
    gleamy@structures@heap@pairing_heap:new(Compare).

-spec from_list(list(GPX), fun((GPX, GPX) -> gleam@order:order())) -> gleamy@structures@heap@pairing_heap:heap(GPX).
from_list(List, Compare) ->
    gleam@list:fold(
        List,
        new(Compare),
        fun gleamy@structures@heap@pairing_heap:insert/2
    ).

-spec pop(gleamy@structures@heap@pairing_heap:heap(GQG)) -> {ok,
        {GQG, gleamy@structures@heap@pairing_heap:heap(GQG)}} |
    {error, nil}.
pop(Queue) ->
    gleamy@structures@heap@pairing_heap:delete_min(Queue).

-spec peek(gleamy@structures@heap@pairing_heap:heap(GQL)) -> {ok, GQL} |
    {error, nil}.
peek(Queue) ->
    gleamy@structures@heap@pairing_heap:find_min(Queue).

-spec push(gleamy@structures@heap@pairing_heap:heap(GQP), GQP) -> gleamy@structures@heap@pairing_heap:heap(GQP).
push(Queue, Item) ->
    gleamy@structures@heap@pairing_heap:insert(Queue, Item).

-spec count(gleamy@structures@heap@pairing_heap:heap(any())) -> integer().
count(Queue) ->
    case gleamy@structures@heap@pairing_heap:delete_min(Queue) of
        {ok, {_, Q}} ->
            count(Q) + 1;

        {error, _} ->
            0
    end.

-spec reorder(
    gleamy@structures@heap@pairing_heap:heap(GQS),
    fun((GQS, GQS) -> gleam@order:order())
) -> gleamy@structures@heap@pairing_heap:heap(GQS).
reorder(Queue, Compare) ->
    case gleamy@structures@heap@pairing_heap:delete_min(Queue) of
        {ok, {X, Q}} ->
            gleamy@structures@heap@pairing_heap:insert(reorder(Q, Compare), X);

        {error, _} ->
            gleamy@structures@heap@pairing_heap:new(Compare)
    end.

-spec to_list(gleamy@structures@heap@pairing_heap:heap(GQV)) -> list(GQV).
to_list(Queue) ->
    case gleamy@structures@heap@pairing_heap:delete_min(Queue) of
        {ok, {X, Q}} ->
            [X | to_list(Q)];

        {error, _} ->
            []
    end.