Add help and color output. (#9)

meson.build

@@ -51,6 +51,8 @@ subdir('src/uenv')
 # the uenv executable
 if uenv_cli
     uenv_src = [
+            'src/cli/color.cpp',
+            'src/cli/help.cpp',
             'src/cli/image.cpp',
             'src/cli/ls.cpp',
             'src/cli/run.cpp',

src/cli/color.cpp

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <unistd.h>
+
+#include <fmt/format.h>
+
+#include "color.h"
+
+namespace color {
+
+namespace impl {
+bool use = true;
+}
+
+void default_color() {
+    // enable color by default
+    set_color(true);
+
+    // disable color if NO_COLOR env. variable is set
+    if (std::getenv("NO_COLOR")) {
+        set_color(false);
+    }
+
+    // disable color if stdout is not a terminal
+    if (!isatty(fileno(stdout))) {
+        set_color(false);
+    }
+}
+
+void set_color(bool v) {
+    impl::use = v;
+}
+
+bool use_color() {
+    return impl::use;
+}
+
+} // namespace color

src/cli/color.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <fmt/color.h>
+
+#define MAKE_COLOR(color)                                                      \
+    static auto color() {                                                      \
+        return fmt::emphasis::bold | fg(fmt::terminal_color::color);           \
+    }                                                                          \
+    template <typename S> constexpr auto color(const S& s) {                   \
+        return use_color() ? fmt::format(color(), "{}", s) : std::string(s);   \
+    }
+
+namespace color {
+
+void default_color();
+void set_color(bool v);
+bool use_color();
+
+MAKE_COLOR(black)
+MAKE_COLOR(red)
+MAKE_COLOR(green)
+MAKE_COLOR(yellow)
+MAKE_COLOR(blue)
+MAKE_COLOR(magenta)
+MAKE_COLOR(cyan)
+MAKE_COLOR(white)
+MAKE_COLOR(bright_black)
+MAKE_COLOR(bright_red)
+MAKE_COLOR(bright_green)
+MAKE_COLOR(bright_yellow)
+MAKE_COLOR(bright_blue)
+MAKE_COLOR(bright_magenta)
+MAKE_COLOR(bright_cyan)
+MAKE_COLOR(bright_white)
+
+} // namespace color

src/cli/help.cpp

@@ -0,0 +1,55 @@
+#include <string>
+
+#include "fmt/format.h"
+
+#include "color.h"
+#include "help.h"
+
+namespace help {
+
+block::block(std::string msg) : kind(none), lines{std::move(msg)} {
+}
+
+std::string render(const linebreak&) {
+    return "";
+}
+
+std::string render(const block& b) {
+    using enum help::block::admonition;
+    std::string result{};
+    switch (b.kind) {
+    case none:
+    case code:
+        break;
+    case note:
+        result += fmt::format("{} - ", ::color::cyan("Note"));
+        break;
+    case xmpl:
+        result += fmt::format("{} - ", ::color::blue("Example"));
+        break;
+    case info:
+        result += fmt::format("{} - ", ::color::green("Info"));
+        break;
+    case warn:
+        result += fmt::format("{} - ", ::color::red("Warning"));
+        break;
+    case depr:
+        result += fmt::format("{} - ", ::color::red("Deprecated"));
+    }
+    bool first = true;
+    for (auto& l : b.lines) {
+        if (!first) {
+            result += "\n";
+        }
+        if (b.kind == code) {
+            result += fmt::format("  {}", ::color::white(l));
+        } else {
+            result += l;
+        }
+        first = false;
+    }
+
+    return result;
+}
+
+} // namespace help

src/cli/help.h

@@ -0,0 +1,126 @@
+#pragma once
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <fmt/color.h>
+#include <fmt/format.h>
+
+#include "color.h"
+
+namespace help {
+
+struct lst {
+    std::string content;
+};
+
+struct block {
+    enum class admonition : std::uint32_t {
+        none,
+        note,
+        xmpl,
+        code,
+        info,
+        warn,
+        depr
+    };
+    using enum admonition;
+    admonition kind = none;
+    std::vector<std::string> lines;
+
+    block() = default;
+    block(std::string);
+    template <typename... Args>
+    block(admonition k, Args&&... args)
+        : kind(k), lines{std::forward<Args>(args)...} {
+    }
+};
+std::string render(const block&);
+
+struct linebreak {};
+std::string render(const linebreak&);
+
+// type erasure for items to print in a help message.
+// any type T for which the following is provided will be supported
+//   std::string render(const T&)
+template <typename T>
+concept Renderable = requires(T v) {
+    { render(v) } -> std::convertible_to<std::string>;
+};
+
+class item {
+  public:
+    template <Renderable T>
+    item(T impl) : impl_(std::make_unique<wrap<T>>(std::move(impl))) {
+    }
+
+    item(item&& other) = default;
+
+    item(const item& other) : impl_(other.impl_->clone()) {
+    }
+
+    item& operator=(item&& other) = default;
+    item& operator=(const item& other) {
+        return *this = item(other);
+    }
+
+    std::string render() const {
+        return impl_->render();
+    }
+
+  private:
+    struct interface {
+        virtual ~interface() {
+        }
+        virtual std::unique_ptr<interface> clone() = 0;
+        virtual std::string render() const = 0;
+    };
+
+    std::unique_ptr<interface> impl_;
+
+    template <Renderable T> struct wrap : interface {
+        explicit wrap(const T& impl) : wrapped(impl) {
+        }
+        explicit wrap(T&& impl) : wrapped(std::move(impl)) {
+        }
+
+        virtual std::unique_ptr<interface> clone() override {
+            return std::unique_ptr<interface>(new wrap<T>(wrapped));
+        }
+
+        virtual std::string render() const override {
+            return help::render(wrapped);
+        }
+
+        T wrapped;
+    };
+};
+
+} // namespace help
+
+template <> class fmt::formatter<help::item> {
+  public:
+    // parse format specification and store it:
+    constexpr auto parse(format_parse_context& ctx) {
+        return ctx.end();
+    }
+    // format a value using stored specification:
+    template <typename FmtContext>
+    constexpr auto format(help::item const& item, FmtContext& ctx) const {
+        return fmt::format_to(ctx.out(), "{}", item.render());
+    }
+};
+
+template <> class fmt::formatter<help::lst> {
+  public:
+    // parse format specification and store it:
+    constexpr auto parse(format_parse_context& ctx) {
+        return ctx.end();
+    }
+    // format a value using stored specification:
+    template <typename FmtContext>
+    constexpr auto format(help::lst const& l, FmtContext& ctx) const {
+        return fmt::format_to(ctx.out(), "{}", ::color::yellow(l.content));
+    }
+};

src/cli/ls.cpp

@@ -1,8 +1,9 @@
 // vim: ts=4 sts=4 sw=4 et
 
-// #include <string>
+#include <string>
 
 #include <fmt/core.h>
+#include <fmt/ranges.h>
 #include <fmt/std.h>
 #include <spdlog/spdlog.h>
 
@@ -11,13 +12,12 @@
 #include <uenv/repository.h>
 #include <util/expected.h>
 
+#include "help.h"
 #include "ls.h"
 
 namespace uenv {
 
-void image_ls_help() {
-    fmt::println("image ls help");
-}
+std::string image_ls_footer();
 
 void image_ls_args::add_cli(CLI::App& cli,
                             [[maybe_unused]] global_settings& settings) {
@@ -28,6 +28,8 @@ void image_ls_args::add_cli(CLI::App& cli,
                      "print only the matching records, with no header.");
     ls_cli->callback(
         [&settings]() { settings.mode = uenv::cli_mode::image_ls; });
+
+    ls_cli->footer(image_ls_footer);
 }
 
 int image_ls(const image_ls_args& args, const global_settings& settings) {
@@ -105,4 +107,53 @@ int image_ls(const image_ls_args& args, const global_settings& settings) {
     return 0;
 }
 
+std::string image_ls_footer() {
+    using enum help::block::admonition;
+    std::vector<help::item> items{
+        // clang-format off
+        help::block{none, "Search for uenv that are available to run." },
+        help::linebreak{},
+        help::block{xmpl, "list all uenv"},
+        help::block{code,   "uenv image ls"},
+        help::linebreak{},
+        help::block{xmpl, "list all uenv"},
+        help::block{code,   "uenv image ls"},
+        help::linebreak{},
+        help::block{xmpl, "list all uenv with the name prgenv-gnu"},
+        help::block{code,   "uenv image ls prgenv-gnu"},
+        help::linebreak{},
+        help::block{xmpl, "list all uenv with the name prgenv-gnu and version 24.7"},
+        help::block{code,   "uenv image ls prgenv-gnu/24.7"},
+        help::linebreak{},
+        help::block{xmpl, "list all uenv with the name prgenv-gnu, version 24.7 and release v2"},
+        help::block{code, "uenv image ls prgenv-gnu/24.7:v2"},
+        help::linebreak{},
+        help::block{xmpl, "use the @ symbol to specify a target system name"},
+        help::block{code,   "uenv image ls prgenv-gnu@todi"},
+        help::block{none, "this feature is useful when using images that were built for a different system",
+                          "than the one you are currently working on."},
+        help::linebreak{},
+        help::block{xmpl, "use the @ symbol to specify a target system name"},
+        help::block{code,   "uenv image ls prgenv-gnu@todi"},
+        help::block{none, "this feature is useful when using images that were built for a different system",
+                          "than the one you are currently working on."},
+        help::linebreak{},
+        help::block{xmpl, "use the % symbol to specify a target microarchitecture (uarch)"},
+        help::block{code,   "uenv image ls prgenv-gnu%gh200"},
+        help::block{none, "this feature is useful on a system with multiple uarch."},
+        help::linebreak{},
+        help::block{xmpl, "list any uenv with a concrete sha256 checksum"},
+        help::block{code,   "uenv image ls 510094ddb3484e305cb8118e21cbb9c94e9aff2004f0d6499763f42" "bdafccfb5"},
+        help::linebreak{},
+        help::block{note, "more than one uenv might be listed if there are two uenv that refer",
+                          "to the same underlying uenv sha256."},
+        help::linebreak{},
+        help::block{xmpl, "search for uenv by id (id is the first 16 characters of the sha256):"},
+        help::block{code,   "uenv image ls 510094ddb3484e30"},
+        // clang-format on
+    };
+
+    return fmt::format("{}", fmt::join(items, "\n"));
+}
+
 } // namespace uenv