"""Rules for vendoring Bazel targets into existing workspaces"""

load("//crate_universe/private:generate_utils.bzl", "compile_config", "render_config")
load("//crate_universe/private:splicing_utils.bzl", "kebab_case_keys", "splicing_config")
load("//crate_universe/private:urls.bzl", "CARGO_BAZEL_LABEL")
load("//rust/platform:triple_mappings.bzl", "SUPPORTED_PLATFORM_TRIPLES")

_UNIX_WRAPPER = """\
#!/usr/bin/env bash
set -euo pipefail
export RUNTIME_PWD="$(pwd)"
if [[ -z "${{BAZEL_REAL:-}}" ]]; then
    BAZEL_REAL="$(which bazel || echo 'bazel')"
fi
eval exec env - BAZEL_REAL="${{BAZEL_REAL}}" BUILD_WORKSPACE_DIRECTORY="${{BUILD_WORKSPACE_DIRECTORY}}" {env} \\
"{bin}" {args} "$@"
"""

_WINDOWS_WRAPPER = """\
@ECHO OFF
set RUNTIME_PWD=%CD%
{env}

call {bin} {args} %@%
"""

CARGO_BAZEL_GENERATOR_PATH = "CARGO_BAZEL_GENERATOR_PATH"

def _runfiles_path(path, is_windows):
    if is_windows:
        runtime_pwd_var = "%RUNTIME_PWD%"
    else:
        runtime_pwd_var = "${RUNTIME_PWD}"
    if path.startswith("../"):
        return "{}/external/{}".format(runtime_pwd_var, path[len("../"):])
    return "{}/{}".format(runtime_pwd_var, path)

def _is_windows(ctx):
    toolchain = ctx.toolchains[Label("@rules_rust//rust:toolchain")]
    return "windows" in toolchain.target_triple

def _get_output_package(ctx):
    # Determine output directory
    if ctx.attr.vendor_path.startswith("/"):
        output = ctx.attr.vendor_path
    else:
        output = "{}/{}".format(
            ctx.label.package,
            ctx.attr.vendor_path,
        )
    return output

def _write_data_file(ctx, name, data):
    file = ctx.actions.declare_file("{}.{}".format(ctx.label.name, name))
    ctx.actions.write(
        output = file,
        content = data,
    )
    return file

def _prepare_manifest_path(target):
    """Generate manifest paths that are resolvable by `cargo_bazel::SplicingManifest::resolve`

    Args:
        target (Target): A `crate_vendor.manifest` target

    Returns:
        str: A string representing the path to a manifest.
    """
    files = target[DefaultInfo].files.to_list()
    if len(files) != 1:
        fail("The manifest {} hand an unexpected number of files: {}".format(
            target.label,
            files,
        ))

    manifest = files[0]

    if target.label.workspace_root.startswith("external"):
        # The short path of an external file is expected to start with `../`
        if not manifest.short_path.startswith("../"):
            fail("Unexpected shortpath for {}: {}".format(
                manifest,
                manifest.short_path,
            ))
        return manifest.short_path.replace("../", "${output_base}/external/", 1)

    return "${build_workspace_directory}/" + manifest.short_path

def _write_splicing_manifest(ctx):
    # Deserialize information about direct packges
    direct_packages_info = {
        # Ensure the data is using kebab-case as that's what `cargo_toml::DependencyDetail` expects.
        pkg: kebab_case_keys(dict(json.decode(data)))
        for (pkg, data) in ctx.attr.packages.items()
    }

    # Manifests are required to be single files
    manifests = {_prepare_manifest_path(m): str(m.label) for m in ctx.attr.manifests}

    config = json.decode(ctx.attr.splicing_config or splicing_config())
    splicing_manifest_content = {
        "cargo_config": _prepare_manifest_path(ctx.attr.cargo_config) if ctx.attr.cargo_config else None,
        "direct_packages": direct_packages_info,
        "manifests": manifests,
    }

    manifest = _write_data_file(
        ctx = ctx,
        name = "cargo-bazel-splicing-manifest.json",
        data = json.encode_indent(
            dict(dict(config).items() + splicing_manifest_content.items()),
            indent = " " * 4,
        ),
    )

    is_windows = _is_windows(ctx)

    args = ["--splicing-manifest", _runfiles_path(manifest.short_path, is_windows)]
    runfiles = [manifest] + ctx.files.manifests + ([ctx.file.cargo_config] if ctx.attr.cargo_config else [])
    return args, runfiles

def _write_config_file(ctx):
    rendering_config = dict(json.decode(render_config(
        regen_command = "bazel run {}".format(
            ctx.label,
        ),
    )))

    output_pkg = _get_output_package(ctx)

    if ctx.attr.mode == "local":
        build_file_base_template = "@{}//{}/{{name}}-{{version}}:BUILD.bazel"
        crate_label_template = "//{}/{{name}}-{{version}}:{{target}}".format(
            output_pkg,
        )
    else:
        build_file_base_template = "@{}//{}:BUILD.{{name}}-{{version}}.bazel"
        crate_label_template = rendering_config["crate_label_template"]

    rendering_config.update({
        "build_file_template": build_file_base_template.format(
            ctx.workspace_name,
            output_pkg,
        ),
        "crate_label_template": crate_label_template,
        "crates_module_template": "@{}//{}:{{file}}".format(
            ctx.workspace_name,
            output_pkg,
        ),
        "vendor_mode": ctx.attr.mode,
    })

    config_data = compile_config(
        crate_annotations = ctx.attr.annotations,
        generate_build_scripts = ctx.attr.generate_build_scripts,
        cargo_config = None,
        render_config = rendering_config,
        supported_platform_triples = ctx.attr.supported_platform_triples,
        repository_name = ctx.attr.repository_name or ctx.label.name,
    )

    config = _write_data_file(
        ctx = ctx,
        name = "cargo-bazel-config.json",
        data = json.encode_indent(
            config_data,
            indent = " " * 4,
        ),
    )

    is_windows = _is_windows(ctx)
    args = ["--config", _runfiles_path(config.short_path, is_windows)]
    runfiles = [config] + ctx.files.manifests
    return args, runfiles

def _crates_vendor_impl(ctx):
    toolchain = ctx.toolchains[Label("@rules_rust//rust:toolchain")]
    is_windows = _is_windows(ctx)

    environ = {
        "CARGO": _runfiles_path(toolchain.cargo.short_path, is_windows),
        "RUSTC": _runfiles_path(toolchain.rustc.short_path, is_windows),
    }

    args = ["vendor"]

    cargo_bazel_runfiles = []

    # Allow action envs to override the use of the cargo-bazel target.
    if CARGO_BAZEL_GENERATOR_PATH in ctx.var:
        bin_path = ctx.var[CARGO_BAZEL_GENERATOR_PATH]
    elif ctx.executable.cargo_bazel:
        bin_path = _runfiles_path(ctx.executable.cargo_bazel.short_path, is_windows)
        cargo_bazel_runfiles.append(ctx.executable.cargo_bazel)
    else:
        fail("{} is missing either the `cargo_bazel` attribute or the '{}' action env".format(
            ctx.label,
            CARGO_BAZEL_GENERATOR_PATH,
        ))

    # Generate config file
    config_args, config_runfiles = _write_config_file(ctx)
    args.extend(config_args)
    cargo_bazel_runfiles.extend(config_runfiles)

    # Generate splicing manifest
    splicing_manifest_args, splicing_manifest_runfiles = _write_splicing_manifest(ctx)
    args.extend(splicing_manifest_args)
    cargo_bazel_runfiles.extend(splicing_manifest_runfiles)

    # Add an optional `Cargo.lock` file.
    if ctx.attr.cargo_lockfile:
        args.extend([
            "--cargo-lockfile",
            _runfiles_path(ctx.file.cargo_lockfile.short_path, is_windows),
        ])
        cargo_bazel_runfiles.extend([ctx.file.cargo_lockfile])

    # Optionally include buildifier
    if ctx.attr.buildifier:
        args.extend(["--buildifier", _runfiles_path(ctx.executable.buildifier.short_path, is_windows)])
        cargo_bazel_runfiles.append(ctx.executable.buildifier)

    # Dtermine platform specific settings
    if is_windows:
        extension = ".bat"
        template = _WINDOWS_WRAPPER
        env_template = "\nset {}={}"
    else:
        extension = ".sh"
        template = _UNIX_WRAPPER
        env_template = "{}={}"

    # Write the wrapper script
    runner = ctx.actions.declare_file(ctx.label.name + extension)
    ctx.actions.write(
        output = runner,
        content = template.format(
            env = " ".join([env_template.format(key, val) for key, val in environ.items()]),
            bin = bin_path,
            args = " ".join(args),
        ),
        is_executable = True,
    )

    return DefaultInfo(
        files = depset([runner]),
        runfiles = ctx.runfiles(
            files = cargo_bazel_runfiles,
            transitive_files = toolchain.all_files,
        ),
        executable = runner,
    )

crates_vendor = rule(
    implementation = _crates_vendor_impl,
    doc = """\
A rule for defining Rust dependencies (crates) and writing targets for them to the current workspace.
This rule is useful for users whose workspaces are expected to be consumed in other workspaces as the
rendered `BUILD` files reduce the number of workspace dependencies, allowing for easier loads. This rule
handles all the same [workflows](#workflows) `crate_universe` rules do.

Example: 

Given the following workspace structure:

```text
[workspace]/
    WORKSPACE
    BUILD
    Cargo.toml
    3rdparty/
        BUILD
    src/
        main.rs
```

The following is something that'd be found in `3rdparty/BUILD`:

```python
load("@rules_rust//crate_universe:defs.bzl", "crates_vendor", "crate")

crates_vendor(
    name = "crates_vendor",
    annotations = {
        "rand": [crate.annotation(
            default_features = False,
            features = ["small_rng"],
        )],
    },
    cargo_lockfile = "//:Cargo.Bazel.lock",
    manifests = ["//:Cargo.toml"],
    mode = "remote",
    vendor_path = "crates",
    tags = ["manual"],
)
```

The above creates a target that can be run to write `BUILD` files into the `3rdparty`
directory next to where the target is defined. To run it, simply call:

```shell
bazel run //3rdparty:crates_vendor
```

<a id="#crates_vendor_repinning_updating_dependencies"></a>

### Repinning / Updating Dependencies

Repinning dependencies is controlled by both the `CARGO_BAZEL_REPIN` environment variable or the `--repin`
flag to the `crates_vendor` binary. To update dependencies, simply add the flag ro your `bazel run` invocation.

```shell
bazel run //3rdparty:crates_vendor -- --repin
```

Under the hood, `--repin` will trigger a [cargo update](https://doc.rust-lang.org/cargo/commands/cargo-update.html)
call against the generated workspace. The following table describes how to controll particular values passed to the
`cargo update` command.

| Value | Cargo command |
| --- | --- |
| Any of [`true`, `1`, `yes`, `on`] | `cargo update` |
| `workspace` | `cargo update --workspace` |
| `package_name` | `cargo upgrade --package package_name` |
| `package_name@1.2.3` | `cargo upgrade --package package_name --precise 1.2.3` |

""",
    attrs = {
        "annotations": attr.string_list_dict(
            doc = "Extra settings to apply to crates. See [crate.annotation](#crateannotation).",
        ),
        "buildifier": attr.label(
            doc = "The path to a [buildifier](https://github.com/bazelbuild/buildtools/blob/5.0.1/buildifier/README.md) binary used to format generated BUILD files.",
            cfg = "exec",
            executable = True,
            default = Label("//crate_universe/private/vendor:buildifier"),
        ),
        "cargo_bazel": attr.label(
            doc = (
                "The cargo-bazel binary to use for vendoring. If this attribute is not set, then a " +
                "`{}` action env will be used.".format(CARGO_BAZEL_GENERATOR_PATH)
            ),
            cfg = "exec",
            executable = True,
            allow_files = True,
            default = CARGO_BAZEL_LABEL,
        ),
        "cargo_config": attr.label(
            doc = "A [Cargo configuration](https://doc.rust-lang.org/cargo/reference/config.html) file.",
            allow_single_file = True,
        ),
        "cargo_lockfile": attr.label(
            doc = "The path to an existing `Cargo.lock` file",
            allow_single_file = True,
        ),
        "generate_build_scripts": attr.bool(
            doc = (
                "Whether or not to generate " +
                "[cargo build scripts](https://doc.rust-lang.org/cargo/reference/build-scripts.html) by default."
            ),
            default = True,
        ),
        "manifests": attr.label_list(
            doc = "A list of Cargo manifests (`Cargo.toml` files).",
            allow_files = ["Cargo.toml"],
        ),
        "mode": attr.string(
            doc = (
                "Flags determining how crates should be vendored. `local` is where crate source and BUILD files are " +
                "written to the repository. `remote` is where only BUILD files are written and repository rules " +
                "used to fetch source code."
            ),
            values = [
                "local",
                "remote",
            ],
            default = "remote",
        ),
        "packages": attr.string_dict(
            doc = "A set of crates (packages) specifications to depend on. See [crate.spec](#crate.spec).",
        ),
        "repository_name": attr.string(
            doc = "The name of the repository to generate for `remote` vendor modes. If unset, the label name will be used",
        ),
        "splicing_config": attr.string(
            doc = (
                "The configuration flags to use for splicing Cargo maniests. Use `//crate_universe:defs.bzl\\%rsplicing_config` to " +
                "generate the value for this field. If unset, the defaults defined there will be used."
            ),
        ),
        "supported_platform_triples": attr.string_list(
            doc = "A set of all platform triples to consider when generating dependencies.",
            default = SUPPORTED_PLATFORM_TRIPLES,
        ),
        "vendor_path": attr.string(
            doc = "The path to a directory to write files into. Absolute paths will be treated as relative to the workspace root",
            default = "crates",
        ),
    },
    executable = True,
    toolchains = ["@rules_rust//rust:toolchain"],
)

def _crates_vendor_remote_repository_impl(repository_ctx):
    build_file = repository_ctx.path(repository_ctx.attr.build_file)
    defs_module = repository_ctx.path(repository_ctx.attr.defs_module)

    repository_ctx.file("BUILD.bazel", repository_ctx.read(build_file))
    repository_ctx.file("defs.bzl", repository_ctx.read(defs_module))
    repository_ctx.file("crates.bzl", "")
    repository_ctx.file("WORKSPACE.bazel", """workspace(name = "{}")""".format(
        repository_ctx.name,
    ))

crates_vendor_remote_repository = repository_rule(
    doc = "Creates a repository paired with `crates_vendor` targets using the `remote` vendor mode.",
    implementation = _crates_vendor_remote_repository_impl,
    attrs = {
        "build_file": attr.label(
            doc = "The BUILD file to use for the root package",
            mandatory = True,
        ),
        "defs_module": attr.label(
            doc = "The `defs.bzl` file to use in the repository",
            mandatory = True,
        ),
    },
)