1 files changed, 248 insertions, 0 deletions
diff --git a/apply.py b/apply.py
new file mode 100755
index 0000000..252f103
--- /dev/null
+++ b/apply.py
@@ -0,0 +1,248 @@
+#!/usr/bin/env python3
+
+import yaml
+import json
+import os
+from pathlib import Path
+import argparse
+from enum import Enum
+import shutil
+
+
+class Applier:
+    def __init__(self):
+        self.links_todo = {}
+        self.dirs_todo = []
+        self.delete_todo = []
+
+    def create_link(self, target: Path, linkpath: Path):
+        if linkpath in self.links_todo:
+            prev = self.links_todo[linkpath]
+            print(f"Link {linkpath} to {target} replaces previus {prev}")
+        self.links_todo[linkpath] = target
+
+    def create_dir(self, path: Path):
+        if path in self.dirs_todo:
+            return
+
+        self.dirs_todo.append(path)
+
+    def delete(self, path: Path):
+        if path in self.delete_todo:
+            return
+
+        self.delete_todo.append(path)
+
+    def apply_dir(self, path: Path, dry_run):
+        print(f"mkdir {path}")
+        if not dry_run:
+            path.mkdir()
+
+    def apply_delete(self, path: Path, dry_run):
+        if path.is_dir():
+            print(f"rmtree {path}!!!")
+            if not dry_run:
+                shutil.rmtree(str(path))
+        else:
+            print(f"remove {path}")
+            if not dry_run:
+                path.unlink()
+
+    def apply_link(self, linkpath: Path, target: Path, dry_run):
+        print(f"link {linkpath} -> {target}")
+        if not dry_run:
+            linkpath.symlink_to(target)
+
+    def apply(self, dry_run=True):
+        for d in self.delete_todo:
+            self.apply_delete(d, dry_run)
+
+        for d in self.dirs_todo:
+            self.apply_dir(d, dry_run)
+
+        for link, target in self.links_todo.items():
+            self.apply_link(link, target, dry_run)
+
+
+def add_or_create(dictio, key, value):
+    if key in dictio:
+        if value not in dictio[key]:
+            dictio[key].append(value)
+    else:
+        dictio[key] = [value]
+
+
+class FileState(Enum):
+    Unused = 1
+    Owned = 2
+    Used = 3
+    links_to_path: Path = Path()
+
+    def can_write(self) -> bool:
+        return self in [FileState.Unused, FileState.Owned]
+
+    def links_to(self) -> str:
+        if self is not FileState.Owned:
+            raise Exception(f"Cannot call location on {self}")
+
+        return self.links_to_path
+
+    @staticmethod
+    def create_owned(links_to: Path) -> "FileState":
+        s = FileState.Owned
+        s.links_to_path = links_to
+        return s
+
+
+class Resolver:
+    def __init__(self, applydir, dotdir, override):
+        self.applydir = Path(applydir)
+        self.applier = Applier()
+        self.dotdir = Path(dotdir)
+        self.override = override
+
+        # Load state
+        self.statefile = Path("state.json")
+        if self.statefile.exists():
+            with self.statefile.open("r") as f:
+                self.state = json.load(f)
+        else:
+            self.state = {"dirs": {}, "links": {}}
+
+        self.stateclean = True
+
+    def dump_state(self):
+        with self.statefile.open("w") as f:
+            json.dump(self.state, f)
+
+    def check_location(self, path: Path) -> FileState:
+        if not path.exists():
+            return FileState.Unused
+
+        if path.is_symlink():
+            dest = Path(os.path.realpath(str(path)))
+            if self.dotdir in dest.parents:
+                return FileState.create_owned(dest)
+
+        return FileState.Used
+
+    def state_save_link(self, dest, packagename):
+        self.state["links"][str(dest)] = packagename
+
+    def check_parent(self, path: Path, packagename):
+        """
+        Check if parents exists, and if we created them mark them
+        with package name
+        """
+
+        parent = path.parent
+        exists = parent.exists()
+        if (not exists) or parent in self.state["dirs"]:
+            self.check_parent(parent, packagename)
+
+            # Add to state
+            add_or_create(self.state["dirs"], str(parent), packagename)
+
+            if not exists:
+                self.applier.create_dir(parent)
+
+    def do_link(self, package, ppath: Path):
+        dest = Path(self.applydir, ppath)
+        dest_state = self.check_location(dest)
+
+        if not self.override and not dest_state.can_write():
+            # Check if it's a pointer to the correct location
+            print(os.readlink(dest))
+            raise Exception(f"Destination {ppath} already exists")
+
+        # Save the link in the statefile
+        self.state_save_link(dest, package)
+
+        self.check_parent(dest, package)
+
+        target_abs = Path.cwd().joinpath(Path(package, ppath))
+        if dest_state == FileState.Owned \
+                and dest_state.links_to() == target_abs:
+            return
+
+        if dest_state != FileState.Unused and self.override:
+            self.applier.delete(dest)
+        self.applier.create_link(target_abs, dest)
+
+    def do_folder_link(self, package, ppath: Path) -> bool:
+        self.do_link(package, ppath)
+        return True
+
+    def apply(self, dry_run=True):
+        self.applier.apply(dry_run)
+
+
+class DirReader:
+    def __init__(self, config, resolv):
+        self.resolv = resolv
+        self.config = config
+
+    def read_package(self, name):
+        package_root = name
+
+        # Walk down and link dir og file
+        for root, dirs, files in os.walk(package_root):
+            rootrel = os.path.relpath(root, start=package_root)
+
+            # Check if we can just link this folder
+            if rootrel not in self.config["do_not_link"]:
+                ok = self.resolv.do_folder_link(name, Path(rootrel))
+
+                if ok:
+                    # Do not go further down
+                    dirs.clear()
+                    continue
+
+            # Link files
+            for f in files:
+                self.resolv.do_link(name, Path(rootrel, f))
+
+
+def parse_config(path):
+    config = {}
+    with open(path, "r") as f:
+        config = yaml.safe_load(f)
+
+    return config
+
+
+parser = argparse.ArgumentParser()
+parser.add_argument("--dot-dir", "-d", default=".",
+                    help="Directory to load dots from")
+parser.add_argument("--apply-dir", "-a", default=None,
+                    help="Directory to load dots from")
+parser.add_argument("--dry-run", "-n", default=False,
+                    help="Do not make filesystem changes", action="store_true")
+parser.add_argument("--override-existing", "-o", default=False,
+                    help="Override existing files,dirs,links",
+                    action="store_true")
+parser.add_argument("packages", nargs="*", help="Packages to apply")
+
+if __name__ == "__main__":
+    args = parser.parse_args()
+
+    # Just cd to dotdir, so everything can make the assumption that cwd
+    # is dotdir
+    os.chdir(args.dot_dir)
+
+    if args.apply_dir is None:
+        args.apply_dir = ".."
+    else:
+        args.apply_dir = str(Path(args.apply_dir).relative_to(args.dot_dir))
+
+    config = parse_config("config.yaml")
+
+    resolv = Resolver(args.apply_dir, Path.cwd(), args.override_existing)
+
+    reader = DirReader(config, resolv)
+    for pack in args.packages:
+        reader.read_package(pack)
+
+    resolv.apply(dry_run=args.dry_run)
+    if args.dry_run:
+        resolv.dump_state()