-module(galchemy@session@loading).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src\\galchemy\\session\\loading.gleam").
-export([eager_join/4, apply_eager/5, lazy_query/4]).
-export_type([load_error/0, eager_load/0, lazy_load/0]).

-type load_error() :: {unknown_table, galchemy@schema@relation:table_ref()} |
    {unknown_relation, galchemy@schema@relation:table_ref(), binary()} |
    {empty_parent_identities, galchemy@schema@relation:table_ref(), binary()} |
    {missing_identity_field,
        galchemy@schema@relation:table_ref(),
        binary(),
        binary()}.

-type eager_load() :: {eager_load,
        galchemy@schema@relation:relation(),
        galchemy@ast@schema:table(),
        galchemy@ast@expression:join()}.

-type lazy_load() :: {lazy_load,
        galchemy@schema@relation:relation(),
        galchemy@ast@query:'query'()}.

-file("src\\galchemy\\session\\loading.gleam", 158).
-spec find_relation_in(list(galchemy@schema@relation:relation()), binary()) -> gleam@option:option(galchemy@schema@relation:relation()).
find_relation_in(Relations, Relation_name) ->
    case Relations of
        [] ->
            none;

        [Next_relation | Rest] ->
            case erlang:element(2, Next_relation) =:= Relation_name of
                true ->
                    {some, Next_relation};

                false ->
                    find_relation_in(Rest, Relation_name)
            end
    end.

-file("src\\galchemy\\session\\loading.gleam", 142).
-spec find_relation(
    galchemy@schema@model:schema_snapshot(),
    galchemy@schema@relation:table_ref(),
    binary()
) -> {ok, galchemy@schema@relation:relation()} | {error, load_error()}.
find_relation(Snapshot, Table, Relation_name) ->
    case galchemy@schema@relation:for_table(
        Snapshot,
        erlang:element(2, Table),
        erlang:element(3, Table)
    ) of
        none ->
            {error, {unknown_table, Table}};

        {some, Table_relations} ->
            case find_relation_in(
                erlang:element(3, Table_relations),
                Relation_name
            ) of
                {some, Next_relation} ->
                    {ok, Next_relation};

                none ->
                    {error, {unknown_relation, Table, Relation_name}}
            end
    end.

-file("src\\galchemy\\session\\loading.gleam", 214).
-spec join_pair_predicate(
    galchemy@ast@schema:table(),
    galchemy@ast@schema:table(),
    galchemy@schema@relation:column_pair()
) -> galchemy@ast@expression:predicate().
join_pair_predicate(Source_table, Related_table, Pair) ->
    {comparison,
        {column_expr, {column_meta, Source_table, erlang:element(2, Pair)}},
        eq,
        {column_expr, {column_meta, Related_table, erlang:element(3, Pair)}}}.

-file("src\\galchemy\\session\\loading.gleam", 193).
-spec join_predicate_rest(
    galchemy@ast@schema:table(),
    galchemy@ast@schema:table(),
    list(galchemy@schema@relation:column_pair()),
    galchemy@ast@expression:predicate()
) -> galchemy@ast@expression:predicate().
join_predicate_rest(Source_table, Related_table, Pairs, Acc) ->
    case Pairs of
        [] ->
            Acc;

        [Pair | Rest] ->
            join_predicate_rest(
                Source_table,
                Related_table,
                Rest,
                {'and',
                    Acc,
                    join_pair_predicate(Source_table, Related_table, Pair)}
            )
    end.

-file("src\\galchemy\\session\\loading.gleam", 173).
-spec join_predicate(
    galchemy@ast@schema:table(),
    galchemy@ast@schema:table(),
    list(galchemy@schema@relation:column_pair())
) -> galchemy@ast@expression:predicate().
join_predicate(Source_table, Related_table, Column_pairs) ->
    case Column_pairs of
        [] ->
            {comparison,
                {value_expr, {bool, true}},
                eq,
                {value_expr, {bool, true}}};

        [First | Rest] ->
            Initial = join_pair_predicate(Source_table, Related_table, First),
            join_predicate_rest(Source_table, Related_table, Rest, Initial)
    end.

-file("src\\galchemy\\session\\loading.gleam", 402).
-spec find_field_value(
    list(galchemy@session@unit_of_work:field_value()),
    binary()
) -> gleam@option:option(galchemy@ast@expression:sql_value()).
find_field_value(Fields, Column_name) ->
    case Fields of
        [] ->
            none;

        [Field_value | Rest] ->
            case erlang:element(2, Field_value) =:= Column_name of
                true ->
                    {some, erlang:element(3, Field_value)};

                false ->
                    find_field_value(Rest, Column_name)
            end
    end.

-file("src\\galchemy\\session\\loading.gleam", 385).
-spec identity_value(
    galchemy@schema@relation:table_ref(),
    binary(),
    galchemy@session@unit_of_work:identity(),
    binary()
) -> {ok, galchemy@ast@expression:sql_value()} | {error, load_error()}.
identity_value(Source_table, Relation_name, Next_identity, Column_name) ->
    case find_field_value(erlang:element(2, Next_identity), Column_name) of
        {some, Value} ->
            {ok, Value};

        none ->
            {error,
                {missing_identity_field,
                    Source_table,
                    Relation_name,
                    Column_name}}
    end.

-file("src\\galchemy\\session\\loading.gleam", 417).
-spec relation_ref_from_table(galchemy@ast@schema:table()) -> galchemy@schema@relation:table_ref().
relation_ref_from_table(Table) ->
    galchemy@schema@relation:table_ref(case erlang:element(2, Table) of
            {some, Schema_name} ->
                Schema_name;

            none ->
                <<"public"/utf8>>
        end, erlang:element(3, Table)).

-file("src\\galchemy\\session\\loading.gleam", 427).
-spec result_try(
    {ok, JCN} | {error, JCO},
    fun((JCN) -> {ok, JCR} | {error, JCO})
) -> {ok, JCR} | {error, JCO}.
result_try(Value, Next) ->
    case Value of
        {ok, Inner} ->
            Next(Inner);

        {error, Error} ->
            {error, Error}
    end.

-file("src\\galchemy\\session\\loading.gleam", 33).
-spec eager_join(
    galchemy@schema@model:schema_snapshot(),
    galchemy@ast@schema:table(),
    binary(),
    gleam@option:option(binary())
) -> {ok, eager_load()} | {error, load_error()}.
eager_join(Snapshot, Source_table, Relation_name, Alias) ->
    Source_ref = relation_ref_from_table(Source_table),
    result_try(
        find_relation(Snapshot, Source_ref, Relation_name),
        fun(Next_relation) ->
            Related_table = {table,
                {some, erlang:element(2, erlang:element(5, Next_relation))},
                erlang:element(3, erlang:element(5, Next_relation)),
                Alias},
            {ok,
                {eager_load,
                    Next_relation,
                    Related_table,
                    {join,
                        left_join,
                        {table_source, Related_table},
                        join_predicate(
                            Source_table,
                            Related_table,
                            erlang:element(6, Next_relation)
                        )}}}
        end
    ).

-file("src\\galchemy\\session\\loading.gleam", 67).
-spec apply_eager(
    galchemy@ast@expression:select_query(),
    galchemy@schema@model:schema_snapshot(),
    galchemy@ast@schema:table(),
    binary(),
    gleam@option:option(binary())
) -> {ok, galchemy@ast@expression:select_query()} | {error, load_error()}.
apply_eager(Select_query, Snapshot, Source_table, Relation_name, Alias) ->
    result_try(
        eager_join(Snapshot, Source_table, Relation_name, Alias),
        fun(Eager) ->
            {ok,
                {select_query,
                    erlang:element(2, Select_query),
                    erlang:element(3, Select_query),
                    erlang:element(4, Select_query),
                    lists:append(
                        erlang:element(5, Select_query),
                        [erlang:element(4, Eager)]
                    ),
                    erlang:element(6, Select_query),
                    erlang:element(7, Select_query),
                    erlang:element(8, Select_query),
                    erlang:element(9, Select_query),
                    erlang:element(10, Select_query),
                    erlang:element(11, Select_query),
                    erlang:element(12, Select_query),
                    erlang:element(13, Select_query)}}
        end
    ).

-file("src\\galchemy\\session\\loading.gleam", 354).
-spec identity_pair_predicate(
    galchemy@schema@relation:table_ref(),
    binary(),
    galchemy@schema@relation:table_ref(),
    galchemy@session@unit_of_work:identity(),
    galchemy@schema@relation:column_pair()
) -> {ok, galchemy@ast@expression:predicate()} | {error, load_error()}.
identity_pair_predicate(
    Source_table,
    Relation_name,
    Related_table,
    Next_identity,
    Pair
) ->
    result_try(
        identity_value(
            Source_table,
            Relation_name,
            Next_identity,
            erlang:element(2, Pair)
        ),
        fun(Value) ->
            Related_ast_table = {table,
                {some, erlang:element(2, Related_table)},
                erlang:element(3, Related_table),
                none},
            {ok,
                {comparison,
                    {column_expr,
                        {column_meta,
                            Related_ast_table,
                            erlang:element(3, Pair)}},
                    eq,
                    {value_expr, Value}}}
        end
    ).

-file("src\\galchemy\\session\\loading.gleam", 323).
-spec identity_predicate_rest(
    galchemy@schema@relation:table_ref(),
    binary(),
    galchemy@schema@relation:table_ref(),
    galchemy@session@unit_of_work:identity(),
    list(galchemy@schema@relation:column_pair()),
    galchemy@ast@expression:predicate()
) -> {ok, galchemy@ast@expression:predicate()} | {error, load_error()}.
identity_predicate_rest(
    Source_table,
    Relation_name,
    Related_table,
    Next_identity,
    Pairs,
    Acc
) ->
    case Pairs of
        [] ->
            {ok, Acc};

        [Pair | Rest] ->
            result_try(
                identity_pair_predicate(
                    Source_table,
                    Relation_name,
                    Related_table,
                    Next_identity,
                    Pair
                ),
                fun(Next_predicate) ->
                    identity_predicate_rest(
                        Source_table,
                        Relation_name,
                        Related_table,
                        Next_identity,
                        Rest,
                        {'and', Acc, Next_predicate}
                    )
                end
            )
    end.

-file("src\\galchemy\\session\\loading.gleam", 290).
-spec identity_predicate(
    galchemy@schema@relation:table_ref(),
    binary(),
    galchemy@schema@relation:relation(),
    galchemy@session@unit_of_work:identity()
) -> {ok, galchemy@ast@expression:predicate()} | {error, load_error()}.
identity_predicate(Source_table, Relation_name, Next_relation, Next_identity) ->
    case erlang:element(6, Next_relation) of
        [] ->
            {error, {empty_parent_identities, Source_table, Relation_name}};

        [First | Rest] ->
            result_try(
                identity_pair_predicate(
                    Source_table,
                    Relation_name,
                    erlang:element(5, Next_relation),
                    Next_identity,
                    First
                ),
                fun(Initial) ->
                    identity_predicate_rest(
                        Source_table,
                        Relation_name,
                        erlang:element(5, Next_relation),
                        Next_identity,
                        Rest,
                        Initial
                    )
                end
            )
    end.

-file("src\\galchemy\\session\\loading.gleam", 262).
-spec lazy_predicate_rest(
    galchemy@schema@relation:table_ref(),
    binary(),
    galchemy@schema@relation:relation(),
    list(galchemy@session@unit_of_work:identity()),
    galchemy@ast@expression:predicate()
) -> {ok, galchemy@ast@expression:predicate()} | {error, load_error()}.
lazy_predicate_rest(Source_table, Relation_name, Next_relation, Identities, Acc) ->
    case Identities of
        [] ->
            {ok, Acc};

        [Next_identity | Rest] ->
            result_try(
                identity_predicate(
                    Source_table,
                    Relation_name,
                    Next_relation,
                    Next_identity
                ),
                fun(Next_predicate) ->
                    lazy_predicate_rest(
                        Source_table,
                        Relation_name,
                        Next_relation,
                        Rest,
                        {'or', Acc, Next_predicate}
                    )
                end
            )
    end.

-file("src\\galchemy\\session\\loading.gleam", 232).
-spec lazy_predicate(
    galchemy@schema@relation:table_ref(),
    binary(),
    galchemy@schema@relation:relation(),
    list(galchemy@session@unit_of_work:identity())
) -> {ok, galchemy@ast@expression:predicate()} | {error, load_error()}.
lazy_predicate(Source_table, Relation_name, Next_relation, Identities) ->
    case Identities of
        [] ->
            {error, {empty_parent_identities, Source_table, Relation_name}};

        [First | Rest] ->
            result_try(
                identity_predicate(
                    Source_table,
                    Relation_name,
                    Next_relation,
                    First
                ),
                fun(Initial) ->
                    lazy_predicate_rest(
                        Source_table,
                        Relation_name,
                        Next_relation,
                        Rest,
                        Initial
                    )
                end
            )
    end.

-file("src\\galchemy\\session\\loading.gleam", 89).
-spec lazy_query(
    galchemy@schema@model:schema_snapshot(),
    galchemy@schema@relation:table_ref(),
    binary(),
    list(galchemy@session@unit_of_work:identity())
) -> {ok, lazy_load()} | {error, load_error()}.
lazy_query(Snapshot, Source_table, Relation_name, Identities) ->
    case Identities of
        [] ->
            {error, {empty_parent_identities, Source_table, Relation_name}};

        _ ->
            result_try(
                find_relation(Snapshot, Source_table, Relation_name),
                fun(Next_relation) ->
                    result_try(
                        lazy_predicate(
                            Source_table,
                            Relation_name,
                            Next_relation,
                            Identities
                        ),
                        fun(Where_) ->
                            Related_table = {table,
                                {some,
                                    erlang:element(
                                        2,
                                        erlang:element(5, Next_relation)
                                    )},
                                erlang:element(
                                    3,
                                    erlang:element(5, Next_relation)
                                ),
                                none},
                            {ok,
                                {lazy_load,
                                    Next_relation,
                                    {select,
                                        {select_query,
                                            [],
                                            [],
                                            {some,
                                                {table_source, Related_table}},
                                            [],
                                            {some, Where_},
                                            [],
                                            none,
                                            [],
                                            [],
                                            none,
                                            none,
                                            false}}}}
                        end
                    )
                end
            )
    end.