feat: Dependency tree command

docs/cli.md

@@ -328,8 +328,6 @@ List project's packages. Highlighted packages are explicit dependencies.
 - `--locked`: Only install if the `pixi.lock` is up-to-date with the [manifest file](configuration.md)[^1]. It can also be controlled by the `PIXI_LOCKED` environment variable (example: `PIXI_LOCKED=true`). Conflicts with `--frozen`.
 - `--no-install`: Don't install the environment for pypi solving, only update the lock-file if it can solve without installing. (Implied by `--frozen` and `--locked`)
 
-```shell
-
 ```shell
 pixi list
 pixi list --json-pretty
@@ -368,6 +366,127 @@ Output will look like this, where `python` will be green as it is the package th
  xz                5.2.6       h166bdaf_0          408.6 KiB  conda  xz-5.2.6-h166bdaf_0.tar.bz2
 ```
 
+## `tree`
+
+Display the project's packages in a tree. Highlighted packages are those specified in the manifest.
+
+The package tree can also be inverted (`-i`), to see which packages require a specific dependencies.
+
+##### Arguments
+
+- `REGEX` optional regex of which direct dependencies to filter the tree to, or which dependencies to start with when inverting the tree.
+
+##### Options
+
+- `--invert (-i)`: Invert the dependency tree, that is given a `REGEX` pattern that matches some packages, show all the packages that depend on those.
+- `--platform <PLATFORM> (-p)`: The platform to list packages for. Defaults to the current platform
+- `--manifest-path <MANIFEST_PATH>`: The path to [manifest file](configuration.md), by default it searches for one in the parent directories.
+- `--environment`(`-e`): The environment's packages to list, if non is provided the default environment's packages will be listed.
+- `--frozen`: Install the environment as defined in the lockfile. Without checking the status of the lockfile. It can also be controlled by the `PIXI_FROZEN` environment variable (example: `PIXI_FROZEN=true`).
+- `--locked`: Only install if the `pixi.lock` is up-to-date with the [manifest file](configuration.md)[^1]. It can also be controlled by the `PIXI_LOCKED` environment variable (example: `PIXI_LOCKED=true`). Conflicts with `--frozen`.
+- `--no-install`: Don't install the environment for pypi solving, only update the lock-file if it can solve without installing. (Implied by `--frozen` and `--locked`)
+
+```shell
+pixi tree
+pixi tree pre-commit
+pixi tree -i yaml
+pixi tree --environment docs
+```
+
+!!! warning
+    Use `-v` to show which `pypi` packages are not yet parsed correctly. The `extras` and `markers` parsing is still under development.
+
+Output will look like this, where direct packages in the [manifest file](configuration.md) will be green.
+Once a package has been displayed once, the tree won't continue to recurse through it's dependencies (compare the first time `livzlib` appears, vs the rest), and it will instead be marked with a star `(*)`.
+
+Version numbers are colored by the package type, yellow for Conda packages and blue for PyPI.
+
+```shell
+➜ pixi tree
+├── pre-commit v3.3.3
+│   ├── cfgv v3.3.1
+│   │   └── python v3.12.2
+│   │       ├── libsqlite v3.45.2
+│   │       │   └── libzlib v1.2.13
+│   │       ├── libzlib v1.2.13 (*)
+│   │       ├── libffi v3.4.2
+│   │       ├── libexpat v2.6.2
+│   │       ├── readline v8.2
+│   │       │   └── ncurses v6.4.20240210
+│   │       ├── xz v5.2.6
+│   │       ├── openssl v3.2.1
+│   │       ├── bzip2 v1.0.8
+│   │       ├── tk v8.6.13
+│   │       │   └── libzlib v1.2.13 (*)
+│   │       └── ncurses v6.4.20240210 (*)
+│   ├── pyyaml v6.0.1
+...
+├── rust v1.76.0
+│   └── rust-std-aarch64-apple-darwin v1.76.0
+├── openssl v3.2.1
+├── pkg-config v0.29.2
+│   ├── libglib v2.78.4
+│   │   ├── libiconv v1.17
+│   │   ├── gettext v0.21.1
+│   │   │   └── libiconv v1.17 (*)
+...
+```
+
+A regex pattern can be specified to filter the tree to just those that show a specific direct dependency:
+
+```shell
+➜ pixi tree pre-commit
+└── pre-commit v3.3.3
+    ├── virtualenv v20.25.1
+    │   ├── filelock v3.13.1
+    │   │   └── python v3.12.2
+    │   │       ├── libexpat v2.6.2
+    │   │       ├── readline v8.2
+    │   │       │   └── ncurses v6.4.20240210
+    │   │       ├── libsqlite v3.45.2
+    │   │       │   └── libzlib v1.2.13
+    │   │       ├── bzip2 v1.0.8
+    │   │       ├── libzlib v1.2.13 (*)
+    │   │       ├── libffi v3.4.2
+    │   │       ├── tk v8.6.13
+    │   │       │   └── libzlib v1.2.13 (*)
+    │   │       ├── xz v5.2.6
+    │   │       ├── ncurses v6.4.20240210 (*)
+    │   │       └── openssl v3.2.1
+    │   ├── platformdirs v4.2.0
+    │   │   └── python v3.12.2 (*)
+    │   ├── distlib v0.3.8
+    │   │   └── python v3.12.2 (*)
+    │   └── python v3.12.2 (*)
+    ├── pyyaml v6.0.1
+...
+```
+
+Additionly the tree can be inverted, and it can show which packages depend on a regex pattern.
+The packages specified in the manifest will also be highlighted (in this case `cffconvert` and `pre-commit` would be).
+
+```shell
+➜ pixi tree -i yaml
+
+ruamel.yaml v0.18.6
+├── pykwalify v1.8.0
+│   └── cffconvert v2.0.0
+└── cffconvert v2.0.0
+
+pyyaml v6.0.1
+└── pre-commit v3.3.3
+
+ruamel.yaml.clib v0.2.8
+└── ruamel.yaml v0.18.6
+    ├── pykwalify v1.8.0
+    │   └── cffconvert v2.0.0
+    └── cffconvert v2.0.0
+
+yaml v0.2.5
+└── pyyaml v6.0.1
+    └── pre-commit v3.3.3
+```
+
 ## `shell`
 
 This command starts a new shell in the project's environment.

src/cli/mod.rs

@@ -23,6 +23,7 @@ pub mod self_update;
 pub mod shell;
 pub mod shell_hook;
 pub mod task;
+pub mod tree;
 pub mod upload;
 
 #[derive(Parser, Debug)]
@@ -75,6 +76,7 @@ pub enum Command {
     Remove(remove::Args),
     SelfUpdate(self_update::Args),
     List(list::Args),
+    Tree(tree::Args),
 }
 
 #[derive(Parser, Debug, Default, Copy, Clone)]
@@ -230,6 +232,7 @@ pub async fn execute_command(command: Command) -> miette::Result<()> {
         Command::Remove(cmd) => remove::execute(cmd).await,
         Command::SelfUpdate(cmd) => self_update::execute(cmd).await,
         Command::List(cmd) => list::execute(cmd).await,
+        Command::Tree(cmd) => tree::execute(cmd).await,
     }
 }