gleam.toml

@@ -18,6 +18,7 @@ gleam_otp = ">= 1.2.0 and < 2.0.0"
 gleam_erlang = ">= 1.3.0 and < 2.0.0"
 simplifile = ">= 2.3.1 and < 3.0.0"
 gleam_json = ">= 3.1.0 and < 4.0.0"
+gleam_time = ">= 1.6.0 and < 2.0.0"
 
 [dev-dependencies]
 gleeunit = ">= 1.0.0 and < 2.0.0"

manifest.toml

@@ -7,6 +7,7 @@ packages = [
   { name = "gleam_json", version = "3.1.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleam_json", source = "hex", outer_checksum = "44FDAA8847BE8FC48CA7A1C089706BD54BADCC4C45B237A992EDDF9F2CDB2836" },
   { name = "gleam_otp", version = "1.2.0", build_tools = ["gleam"], requirements = ["gleam_erlang", "gleam_stdlib"], otp_app = "gleam_otp", source = "hex", outer_checksum = "BA6A294E295E428EC1562DC1C11EA7530DCB981E8359134BEABC8493B7B2258E" },
   { name = "gleam_stdlib", version = "0.65.0", build_tools = ["gleam"], requirements = [], otp_app = "gleam_stdlib", source = "hex", outer_checksum = "7C69C71D8C493AE11A5184828A77110EB05A7786EBF8B25B36A72F879C3EE107" },
+  { name = "gleam_time", version = "1.6.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleam_time", source = "hex", outer_checksum = "0DF3834D20193F0A38D0EB21F0A78D48F2EC276C285969131B86DF8D4EF9E762" },
   { name = "gleeunit", version = "1.9.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleeunit", source = "hex", outer_checksum = "DA9553CE58B67924B3C631F96FE3370C49EB6D6DC6B384EC4862CC4AAA718F3C" },
   { name = "simplifile", version = "2.3.1", build_tools = ["gleam"], requirements = ["filepath", "gleam_stdlib"], otp_app = "simplifile", source = "hex", outer_checksum = "957E0E5B75927659F1D2A1B7B75D7B9BA96FAA8D0C53EA71C4AD9CD0C6B848F6" },
 ]
@@ -16,5 +17,6 @@ gleam_erlang = { version = ">= 1.3.0 and < 2.0.0" }
 gleam_json = { version = ">= 3.1.0 and < 4.0.0" }
 gleam_otp = { version = ">= 1.2.0 and < 2.0.0" }
 gleam_stdlib = { version = ">= 0.44.0 and < 2.0.0" }
+gleam_time = { version = ">= 1.6.0 and < 2.0.0" }
 gleeunit = { version = ">= 1.0.0 and < 2.0.0" }
 simplifile = { version = ">= 2.3.1 and < 3.0.0" }

src/musicplayer/logging/control.gleam

@@ -0,0 +1,7 @@
+import gleam/erlang/process.{type Subject}
+
+pub type Control {
+  Write(String)
+
+  Exit(reply_to: Subject(Nil))
+}

src/musicplayer/logging/logging.gleam

@@ -0,0 +1,58 @@
+import gleam/erlang/process.{type Subject}
+import gleam/otp/actor
+import gleam/result
+import gleam/string
+import gleam/time/calendar
+import gleam/time/timestamp
+import simplifile
+
+import musicplayer/logging/control.{type Control}
+
+type State {
+  State(filepath: String)
+}
+
+pub fn new(filepath: String) -> Result(Subject(Control), String) {
+  use _ <- result.try(
+    case simplifile.is_file(filepath) {
+      Ok(True) -> Ok(Nil)
+      _ -> simplifile.create_file(filepath)
+    }
+    |> result.map_error(fn(e) {
+      "Could not access or create log file: " <> string.inspect(e)
+    }),
+  )
+
+  actor.new(State(filepath:))
+  |> actor.on_message(handle_message)
+  |> actor.start
+  |> result.map_error(fn(start_error) {
+    "Could not start logger: " <> string.inspect(start_error)
+  })
+  |> result.map(fn(started) { started.data })
+}
+
+fn handle_message(state: State, control: Control) -> actor.Next(State, Control) {
+  case control {
+    control.Write(content) -> {
+      let log_line =
+        timestamp.system_time()
+        |> timestamp.to_rfc3339(calendar.utc_offset)
+        <> ": "
+        <> content
+        <> "\n"
+
+      // Ignore any logging errors
+      let _ = simplifile.append(state.filepath, log_line)
+      actor.continue(state)
+    }
+    control.Exit(reply_to) -> {
+      process.send(reply_to, Nil)
+      actor.stop()
+    }
+  }
+}
+
+pub fn log(logger: Subject(Control), content: String) -> Nil {
+  process.send(logger, control.Write(content))
+}