just-mr: Add utility getters for alternative mirrors specifications

2 files changed, 73 insertions, 1 deletions

diff --git a/src/other_tools/just_mr/TARGETS b/src/other_tools/just_mr/TARGETS
index d98d2e60..c4a75aef 100644
--- a/src/other_tools/just_mr/TARGETS
+++ b/src/other_tools/just_mr/TARGETS
@@ -190,7 +190,7 @@
   { "type": ["@", "rules", "CC", "library"]
   , "name": ["mirrors"]
   , "hdrs": ["mirrors.hpp"]
-  , "deps": [["@", "json", "", "json"]]
+  , "deps": [["@", "json", "", "json"], ["src/buildtool/logging", "logging"]]
   , "stage": ["src", "other_tools", "just_mr"]
   }
 }
diff --git a/src/other_tools/just_mr/mirrors.hpp b/src/other_tools/just_mr/mirrors.hpp
index d59300c5..286a9f0c 100644
--- a/src/other_tools/just_mr/mirrors.hpp
+++ b/src/other_tools/just_mr/mirrors.hpp
@@ -16,8 +16,11 @@
 #define INCLUDED_SRC_OTHER_TOOLS_JUST_MR_MIRRORS_HPP
 
 #include <memory>
+#include <string>
+#include <vector>
 
 #include "nlohmann/json.hpp"
+#include "src/buildtool/logging/logger.hpp"
 
 struct Mirrors {
     nlohmann::json local_mirrors{};        // maps URLs to list of local mirrors
@@ -26,4 +29,73 @@ struct Mirrors {
 
 using MirrorsPtr = std::shared_ptr<Mirrors>;
 
+namespace MirrorsUtils {
+
+/// \brief Get the list of local mirrors for given primary URL.
+[[nodiscard]] static inline auto GetLocalMirrors(
+    MirrorsPtr const& additional_mirrors,
+    std::string const& repo_url) noexcept -> std::vector<std::string> {
+    try {
+        if (additional_mirrors->local_mirrors.contains(repo_url)) {
+            auto const& arr = additional_mirrors->local_mirrors[repo_url];
+            if (arr.is_array()) {
+                std::vector<std::string> res{};
+                res.reserve(arr.size());
+                for (auto const& [_, val] : arr.items()) {
+                    if (val.is_string()) {
+                        res.emplace_back(val.get<std::string>());
+                    }
+                    else {
+                        Logger::Log(LogLevel::Warning,
+                                    "Retrieving additional mirrors: found "
+                                    "non-string list entry {}",
+                                    val.dump());
+                        return {};
+                    }
+                }
+                return res;
+            }
+            Logger::Log(
+                LogLevel::Warning,
+                "Retrieving additional mirrors: found non-list value {}",
+                arr.dump());
+        }
+    } catch (std::exception const& ex) {
+        Logger::Log(LogLevel::Warning,
+                    "Retrieving additional mirrors failed with:\n{}",
+                    ex.what());
+    }
+    return {};
+}
+
+/// \brief Get the list of preferred hostnames for non-local fetches.
+[[nodiscard]] static inline auto GetPreferredHostnames(
+    MirrorsPtr const& additional_mirrors) noexcept -> std::vector<std::string> {
+    try {
+        std::vector<std::string> res{};
+        res.reserve(additional_mirrors->preferred_hostnames.size());
+        for (auto const& [_, val] :
+             additional_mirrors->preferred_hostnames.items()) {
+            if (val.is_string()) {
+                res.emplace_back(val.get<std::string>());
+            }
+            else {
+                Logger::Log(LogLevel::Warning,
+                            "Retrieving preferred mirrors: found non-string "
+                            "list entry {}",
+                            val.dump());
+                return {};
+            }
+        }
+        return res;
+    } catch (std::exception const& ex) {
+        Logger::Log(LogLevel::Warning,
+                    "Retrieving preferred mirrors failed with:\n{}",
+                    ex.what());
+        return {};
+    };
+}
+
+}  // namespace MirrorsUtils
+
 #endif  // INCLUDED_SRC_OTHER_TOOLS_JUST_MR_MIRRORS_HPP