refactor patch management and add ownership safeguards

1 files changed, 175 insertions, 0 deletions

diff --git a/backend/config.py b/backend/config.py
new file mode 100644
index 0000000..87476cc
--- /dev/null
+++ b/backend/config.py
@@ -0,0 +1,175 @@
+"""OptiScaler configuration migration and default handling."""
+
+import re
+from pathlib import Path
+from typing import Callable
+
+
+Logger = Callable[[str], None]
+
+
+def _split_override_key(raw_key: str) -> tuple[str | None, str]:
+    key = str(raw_key).strip()
+    if "." in key:
+        section, section_key = key.split(".", 1)
+        section = section.strip()
+        section_key = section_key.strip()
+        if section and section_key:
+            return section, section_key
+    return None, key
+
+
+def apply_overrides(ini_file: Path, overrides: dict, logger: Logger | None = None) -> bool:
+    """Upsert INI keys without disturbing unrelated game configuration."""
+    if not overrides:
+        return True
+    try:
+        content = ini_file.read_text(encoding="utf-8", errors="replace")
+        newline = "\r\n" if "\r\n" in content else "\n"
+        lines = content.splitlines(keepends=True)
+        section_pattern = re.compile(r"^\s*\[(?P<section>[^\]]+)\]\s*$")
+
+        def ensure_trailing_newline() -> None:
+            if lines and not lines[-1].endswith(("\n", "\r")):
+                lines[-1] += newline
+
+        def upsert(section: str | None, key: str, value: str) -> None:
+            replacement = f"{key}={value}"
+            key_pattern = re.compile(rf"^(\s*{re.escape(key)}\s*)=.*$")
+
+            if section is None:
+                for index, line in enumerate(lines):
+                    if key_pattern.match(line):
+                        ending = "\r\n" if line.endswith("\r\n") else ("\n" if line.endswith("\n") else newline)
+                        lines[index] = f"{replacement}{ending}"
+                        return
+                ensure_trailing_newline()
+                lines.append(f"{replacement}{newline}")
+                return
+
+            in_section = False
+            insert_at = None
+            for index, line in enumerate(lines):
+                match = section_pattern.match(line.strip())
+                if match:
+                    if in_section:
+                        insert_at = index
+                        break
+                    if match.group("section") == section:
+                        in_section = True
+                        continue
+                if in_section and key_pattern.match(line):
+                    ending = "\r\n" if line.endswith("\r\n") else ("\n" if line.endswith("\n") else newline)
+                    lines[index] = f"{replacement}{ending}"
+                    return
+
+            if in_section:
+                if insert_at is None:
+                    ensure_trailing_newline()
+                    insert_at = len(lines)
+                lines.insert(insert_at, f"{replacement}{newline}")
+                return
+
+            ensure_trailing_newline()
+            if lines and lines[-1].strip():
+                lines.append(newline)
+            lines.extend((f"[{section}]{newline}", f"{replacement}{newline}"))
+
+        for raw_key, raw_value in overrides.items():
+            section, key = _split_override_key(str(raw_key))
+            if key:
+                upsert(section, key, str(raw_value).strip())
+        ini_file.write_text("".join(lines), encoding="utf-8")
+        return True
+    except Exception as exc:
+        if logger:
+            logger(f"Failed to apply OptiScaler.ini overrides to {ini_file}: {exc}")
+        return False
+
+
+def migrate(ini_file: Path, logger: Logger | None = None) -> bool:
+    """Migrate the pre-0.9 ``FGType`` setting to split input/output keys."""
+    try:
+        if not ini_file.exists():
+            return False
+        content = ini_file.read_text(encoding="utf-8", errors="replace")
+        match = re.search(r"^FGType\s*=\s*(\S+)", content, re.MULTILINE)
+        if not match:
+            return True
+
+        value = match.group(1)
+        if re.search(r"^FGInput\s*=", content, re.MULTILINE):
+            updated = re.sub(r"^FGType\s*=\s*\S+\n?", "", content, flags=re.MULTILINE)
+            message = f"Removed stale FGType from {ini_file}"
+        else:
+            updated = re.sub(
+                r"^FGType\s*=\s*\S+",
+                f"FGInput={value}\nFGOutput={value}",
+                content,
+                flags=re.MULTILINE,
+            )
+            message = f"Migrated FGType={value} in {ini_file}"
+        if updated != content:
+            ini_file.write_text(updated, encoding="utf-8")
+            if logger:
+                logger(message)
+        return True
+    except Exception as exc:
+        if logger:
+            logger(f"Failed to migrate OptiScaler.ini: {exc}")
+        return False
+
+
+def disable_hq_font_auto(ini_file: Path, logger: Logger | None = None) -> bool:
+    """Avoid the HQ font auto mode, which is unreliable under Proton."""
+    try:
+        if not ini_file.exists():
+            return False
+        content = ini_file.read_text(encoding="utf-8", errors="replace")
+        updated = re.sub(r"UseHQFont\s*=\s*auto", "UseHQFont=false", content)
+        if updated != content:
+            ini_file.write_text(updated, encoding="utf-8")
+        return True
+    except Exception as exc:
+        if logger:
+            logger(f"Failed to update HQ font setting in {ini_file}: {exc}")
+        return False
+
+
+def configure(
+    ini_file: Path,
+    framegen_backend: str,
+    variant_overrides: dict | None = None,
+    logger: Logger | None = None,
+) -> bool:
+    """Apply safe defaults and the selected frame-generation backend."""
+    if not ini_file.exists():
+        return False
+    backend = framegen_backend if framegen_backend in {"auto", "nukems"} else "auto"
+    overrides = {
+        "FGInput": backend,
+        "FGOutput": backend,
+        "Fsr4Update": "true",
+        "LoadAsiPlugins": "true",
+    }
+    if variant_overrides:
+        overrides.update(variant_overrides)
+    migrated = migrate(ini_file, logger)
+    hq_updated = disable_hq_font_auto(ini_file, logger)
+    configured = apply_overrides(ini_file, overrides, logger)
+    return migrated and hq_updated and configured
+
+
+def detect_backend(ini_file: Path) -> str:
+    """Return the configured backend when both FG keys agree."""
+    try:
+        content = ini_file.read_text(encoding="utf-8", errors="replace")
+    except OSError:
+        return "auto"
+    values = [
+        match.group(1).strip().lower()
+        for match in re.finditer(r"^FG(?:Input|Output)\s*=\s*(\S+)", content, re.MULTILINE)
+    ]
+    if values and all(value == "nukems" for value in values):
+        return "nukems"
+    return "auto"