-module(gorrion).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/gorrion.gleam").
-export([migrate/2, rollback/2, rollback_to/3, status/2]).

-if(?OTP_RELEASE >= 27).
-define(MODULEDOC(Str), -moduledoc(Str)).
-define(DOC(Str), -doc(Str)).
-else.
-define(MODULEDOC(Str), -compile([])).
-define(DOC(Str), -compile([])).
-endif.

?MODULEDOC(
    " Gorrion — Ecto-like database migration library for Gleam.\n"
    "\n"
    " Reads migration SQL from .sql files on disk, tracks applied migrations\n"
    " in a _schema_migrations table, and supports forward migration and rollback.\n"
    "\n"
    " ## Usage\n"
    "\n"
    " ```gleam\n"
    " // Run all pending migrations\n"
    " gorrion.migrate(db, \"migrations\")\n"
    "\n"
    " // Roll back the most recent migration\n"
    " gorrion.rollback(db, \"migrations\")\n"
    "\n"
    " // Check migration status\n"
    " gorrion.status(db, \"migrations\")\n"
    " ```\n"
).

-file("src/gorrion.gleam", 137).
?DOC(
    " Internal: ensure tracking table exists, get applied migrations,\n"
    " and compute which migrations are pending.\n"
).
-spec resolve(pog:connection(), list(gorrion@types:migration())) -> {ok,
        {list(gorrion@types:migration()),
            list(gorrion@types:applied_migration())}} |
    {error, gorrion@types:migration_error()}.
resolve(Db, Migrations) ->
    gleam@result:'try'(
        gorrion@tracker:ensure_table(Db),
        fun(_) ->
            gleam@result:'try'(
                gorrion@tracker:get_applied(Db),
                fun(Applied) ->
                    Applied_versions = begin
                        _pipe = Applied,
                        _pipe@1 = gleam@list:map(
                            _pipe,
                            fun(A) -> erlang:element(2, A) end
                        ),
                        gleam@set:from_list(_pipe@1)
                    end,
                    Pending = begin
                        _pipe@2 = Migrations,
                        _pipe@3 = gleam@list:filter(
                            _pipe@2,
                            fun(M) ->
                                not gleam@set:contains(
                                    Applied_versions,
                                    erlang:element(2, M)
                                )
                            end
                        ),
                        gleam@list:sort(
                            _pipe@3,
                            fun(A@1, B) ->
                                gleam@int:compare(
                                    erlang:element(2, A@1),
                                    erlang:element(2, B)
                                )
                            end
                        )
                    end,
                    {ok, {Pending, Applied}}
                end
            )
        end
    ).

-file("src/gorrion.gleam", 33).
?DOC(" Run all pending migrations in version order.\n").
-spec migrate(pog:connection(), binary()) -> {ok, nil} |
    {error, gorrion@types:migration_error()}.
migrate(Db, Dir) ->
    gleam@result:'try'(
        gorrion@loader:load_migrations(Dir),
        fun(Migrations) ->
            gleam@result:'try'(
                resolve(Db, Migrations),
                fun(_use0) ->
                    {Pending, _} = _use0,
                    case Pending of
                        [] ->
                            gleam_stdlib:println(
                                <<"No pending migrations"/utf8>>
                            ),
                            {ok, nil};

                        _ ->
                            gleam_stdlib:println(
                                <<<<"Applying "/utf8,
                                        (erlang:integer_to_binary(
                                            erlang:length(Pending)
                                        ))/binary>>/binary,
                                    " pending migration(s)..."/utf8>>
                            ),
                            gleam@list:try_fold(
                                Pending,
                                nil,
                                fun(_, M) ->
                                    gorrion@runner:apply_migration(Db, M)
                                end
                            )
                    end
                end
            )
        end
    ).

-file("src/gorrion.gleam", 57).
?DOC(" Roll back the most recently applied migration.\n").
-spec rollback(pog:connection(), binary()) -> {ok, nil} |
    {error, gorrion@types:migration_error()}.
rollback(Db, Dir) ->
    gleam@result:'try'(
        gorrion@loader:load_migrations(Dir),
        fun(Migrations) ->
            gleam@result:'try'(
                resolve(Db, Migrations),
                fun(_use0) ->
                    {_, Applied} = _use0,
                    Applied_versions = begin
                        _pipe = Applied,
                        _pipe@1 = gleam@list:map(
                            _pipe,
                            fun(A) -> erlang:element(2, A) end
                        ),
                        gleam@set:from_list(_pipe@1)
                    end,
                    Latest = begin
                        _pipe@2 = Migrations,
                        _pipe@3 = gleam@list:filter(
                            _pipe@2,
                            fun(M) ->
                                gleam@set:contains(
                                    Applied_versions,
                                    erlang:element(2, M)
                                )
                            end
                        ),
                        _pipe@4 = gleam@list:sort(
                            _pipe@3,
                            fun(A@1, B) ->
                                gleam@int:compare(
                                    erlang:element(2, B),
                                    erlang:element(2, A@1)
                                )
                            end
                        ),
                        gleam@list:first(_pipe@4)
                    end,
                    case Latest of
                        {error, _} ->
                            {error, no_migrations_to_rollback};

                        {ok, Migration} ->
                            gleam_stdlib:println(
                                <<"Rolling back 1 migration..."/utf8>>
                            ),
                            gorrion@runner:revert_migration(Db, Migration)
                    end
                end
            )
        end
    ).

-file("src/gorrion.gleam", 86).
?DOC(" Roll back all migrations down to (but not including) the target version.\n").
-spec rollback_to(pog:connection(), binary(), integer()) -> {ok, nil} |
    {error, gorrion@types:migration_error()}.
rollback_to(Db, Dir, Target) ->
    gleam@result:'try'(
        gorrion@loader:load_migrations(Dir),
        fun(Migrations) ->
            gleam@result:'try'(
                resolve(Db, Migrations),
                fun(_use0) ->
                    {_, Applied} = _use0,
                    Applied_versions = begin
                        _pipe = Applied,
                        _pipe@1 = gleam@list:map(
                            _pipe,
                            fun(A) -> erlang:element(2, A) end
                        ),
                        gleam@set:from_list(_pipe@1)
                    end,
                    To_revert = begin
                        _pipe@2 = Migrations,
                        _pipe@3 = gleam@list:filter(
                            _pipe@2,
                            fun(M) ->
                                gleam@set:contains(
                                    Applied_versions,
                                    erlang:element(2, M)
                                )
                                andalso (erlang:element(2, M) > Target)
                            end
                        ),
                        gleam@list:sort(
                            _pipe@3,
                            fun(A@1, B) ->
                                gleam@int:compare(
                                    erlang:element(2, B),
                                    erlang:element(2, A@1)
                                )
                            end
                        )
                    end,
                    case To_revert of
                        [] ->
                            gleam_stdlib:println(
                                <<"No migrations to roll back"/utf8>>
                            ),
                            {ok, nil};

                        _ ->
                            gleam_stdlib:println(
                                <<<<"Rolling back "/utf8,
                                        (erlang:integer_to_binary(
                                            erlang:length(To_revert)
                                        ))/binary>>/binary,
                                    " migration(s)..."/utf8>>
                            ),
                            gleam@list:try_fold(
                                To_revert,
                                nil,
                                fun(_, M@1) ->
                                    gorrion@runner:revert_migration(Db, M@1)
                                end
                            )
                    end
                end
            )
        end
    ).

-file("src/gorrion.gleam", 126).
?DOC(" Get the current migration status: which are applied and which are pending.\n").
-spec status(pog:connection(), binary()) -> {ok,
        gorrion@types:migration_status()} |
    {error, gorrion@types:migration_error()}.
status(Db, Dir) ->
    gleam@result:'try'(
        gorrion@loader:load_migrations(Dir),
        fun(Migrations) ->
            gleam@result:'try'(
                resolve(Db, Migrations),
                fun(_use0) ->
                    {Pending, Applied} = _use0,
                    {ok, {migration_status, Applied, Pending}}
                end
            )
        end
    ).