Refactor Figure.text to make it more readable/maintainable (#3365)

pygmt/src/text.py

@@ -179,55 +179,61 @@ def text_(  # noqa: PLR0912
     kwargs = self._preprocess(**kwargs)
 
     # Ensure inputs are either textfiles, x/y/text, or position/text
-    if position is None:
-        if any(v is not None for v in (x, y, text)) and textfiles is not None:
-            raise GMTInvalidInput(
-                "Provide either position only, or x/y pairs, or textfiles."
-            )
-        kind = data_kind(textfiles)
-        if kind == "vectors" and text is None:
-            raise GMTInvalidInput("Must provide text with x/y pairs")
-    else:
-        if any(v is not None for v in (x, y, textfiles)):
-            raise GMTInvalidInput(
-                "Provide either position only, or x/y pairs, or textfiles."
-            )
-        if text is None or is_nonstr_iter(text):
-            raise GMTInvalidInput("Text can't be None or array.")
-        kind = None
-        textfiles = ""
+    if (
+        (textfiles is not None)
+        + (position is not None)
+        + (x is not None or y is not None)
+    ) != 1:
+        raise GMTInvalidInput("Provide either textfiles, x/y/text, or position/text.")
+
+    required_data = position is None
+    kind = data_kind(textfiles, required=required_data)
 
-    # Build the -F option in gmt text.
+    if position is not None and (text is None or is_nonstr_iter(text)):
+        raise GMTInvalidInput("'text' can't be None or array when 'position' is given.")
+    if textfiles is not None and text is not None:
+        raise GMTInvalidInput("'text' can't be specified when 'textfiles' is given.")
+    if kind == "vectors" and text is None:
+        raise GMTInvalidInput("Must provide text with x/y pairs.")
+
+    # Arguments that can accept arrays.
+    array_args = [
+        (angle, "+a", "angle"),
+        (font, "+f", "font"),
+        (justify, "+j", "justify"),
+    ]
+
+    # Build the -F option.
     if kwargs.get("F") is None and any(
         v is not None for v in (position, angle, font, justify)
     ):
         kwargs.update({"F": ""})
 
-    extra_arrays = []
-    for arg, flag in [(angle, "+a"), (font, "+f"), (justify, "+j")]:
+    for arg, flag, _ in array_args:
         if arg is True:
             kwargs["F"] += flag
-        elif is_nonstr_iter(arg):
-            kwargs["F"] += flag
-            if flag == "+a":  # angle is numeric type
-                extra_arrays.append(np.atleast_1d(arg))
-            else:  # font or justify is str type
-                extra_arrays.append(np.atleast_1d(arg).astype(str))
         elif isinstance(arg, int | float | str):
             kwargs["F"] += f"{flag}{arg}"
 
-    if isinstance(position, str):
-        kwargs["F"] += f"+c{position}+t{text}"
-
-    # If an array of transparency is given, GMT will read it from
-    # the last numerical column per data record.
-    if is_nonstr_iter(kwargs.get("t")):
-        extra_arrays.append(kwargs["t"])
-        kwargs["t"] = ""
-
-    # Append text at last column. Text must be passed in as str type.
+    extra_arrays = []
     confdict = {}
     if kind == "vectors":
+        for arg, flag, name in array_args:
+            if is_nonstr_iter(arg):
+                kwargs["F"] += flag
+                # angle is numeric type and font/justify are str type.
+                if name == "angle":
+                    extra_arrays.append(np.atleast_1d(arg))
+                else:
+                    extra_arrays.append(np.atleast_1d(arg).astype(str))
+
+        # If an array of transparency is given, GMT will read it from the last numerical
+        # column per data record.
+        if is_nonstr_iter(kwargs.get("t")):
+            extra_arrays.append(np.atleast_1d(kwargs["t"]))
+            kwargs["t"] = True
+
+        # Append text to the last column. Text must be passed in as str type.
         text = np.atleast_1d(text).astype(str)
         encoding = _check_encoding("".join(text))
         if encoding != "ascii":
@@ -238,10 +244,23 @@ def text_(  # noqa: PLR0912
 
         if encoding not in {"ascii", "ISOLatin1+"}:
             confdict = {"PS_CHAR_ENCODING": encoding}
+    else:
+        if isinstance(position, str):
+            kwargs["F"] += f"+c{position}+t{text}"
+
+        for arg, _, name in [*array_args, (kwargs.get("t"), "", "transparency")]:
+            if is_nonstr_iter(arg):
+                msg = f"Argument of '{name}' must be a single value or True."
+                raise GMTInvalidInput(msg)
 
     with Session() as lib:
         with lib.virtualfile_in(
-            check_kind="vector", data=textfiles, x=x, y=y, extra_arrays=extra_arrays
+            check_kind="vector",
+            data=textfiles,
+            x=x,
+            y=y,
+            extra_arrays=extra_arrays,
+            required_data=required_data,
         ) as vintbl:
             lib.call_module(
                 module="text",