1 files changed, 159 insertions, 0 deletions
diff --git a/lua/mason-core/managers/gem/init.lua b/lua/mason-core/managers/gem/init.lua
new file mode 100644
index 00000000..11019985
--- /dev/null
+++ b/lua/mason-core/managers/gem/init.lua
@@ -0,0 +1,159 @@
+local _ = require "mason-core.functional"
+local process = require "mason-core.process"
+local path = require "mason-core.path"
+local Result = require "mason-core.result"
+local spawn = require "mason-core.spawn"
+local Optional = require "mason-core.optional"
+local installer = require "mason-core.installer"
+local platform = require "mason-core.platform"
+
+local M = {}
+
+local create_bin_path = _.compose(path.concat, function(executable)
+    return _.append(executable, { "bin" })
+end, _.if_else(_.always(platform.is.win), _.format "%s.cmd", _.identity))
+
+---@param packages string[]
+local function with_receipt(packages)
+    return function()
+        local ctx = installer.context()
+        ctx.receipt:with_primary_source(ctx.receipt.gem(packages[1]))
+        for i = 2, #packages do
+            ctx.receipt:with_secondary_source(ctx.receipt.gem(packages[i]))
+        end
+    end
+end
+
+---@async
+---@param packages { [number]: string, bin: string[] | nil } @The Gem packages to install. The first item in this list will be the recipient of the requested version, if set.
+function M.packages(packages)
+    return function()
+        return M.install(packages).with_receipt()
+    end
+end
+
+---@async
+---@param packages { [number]: string, bin: string[] | nil } @The Gem packages to install. The first item in this list will be the recipient of the requested version, if set.
+function M.install(packages)
+    local ctx = installer.context()
+    local pkgs = _.list_copy(packages or {})
+
+    ctx.requested_version:if_present(function(version)
+        pkgs[1] = ("%s:%s"):format(pkgs[1], version)
+    end)
+
+    ctx.spawn.gem {
+        "install",
+        "--no-user-install",
+        "--install-dir=.",
+        "--bindir=bin",
+        "--no-document",
+        pkgs,
+    }
+
+    if packages.bin then
+        _.each(function(executable)
+            ctx:link_bin(executable, create_bin_path(executable))
+        end, packages.bin)
+    end
+
+    return {
+        with_receipt = with_receipt(packages),
+    }
+end
+
+---@alias GemOutdatedPackage {name:string, current_version: string, latest_version: string}
+
+---Parses a string input like "package (0.1.0 < 0.2.0)" into its components
+---@param outdated_gem string
+---@return GemOutdatedPackage
+function M.parse_outdated_gem(outdated_gem)
+    local package_name, version_expression = outdated_gem:match "^(.+) %((.+)%)"
+    if not package_name or not version_expression then
+        -- unparseable
+        return nil
+    end
+    local current_version, latest_version = unpack(vim.split(version_expression, "<"))
+
+    ---@type GemOutdatedPackage
+    local outdated_package = {
+        name = vim.trim(package_name),
+        current_version = vim.trim(current_version),
+        latest_version = vim.trim(latest_version),
+    }
+    return outdated_package
+end
+
+---Parses the stdout of the `gem list` command into a table<package_name, version>
+---@param output string
+function M.parse_gem_list_output(output)
+    ---@type table<string, string>
+    local gem_versions = {}
+    for _, line in ipairs(vim.split(output, "\n")) do
+        local gem_package, version = line:match "^(%S+) %((%S+)%)$"
+        if gem_package and version then
+            gem_versions[gem_package] = version
+        end
+    end
+    return gem_versions
+end
+
+local function not_empty(s)
+    return s ~= nil and s ~= ""
+end
+
+---@async
+---@param receipt InstallReceipt
+---@param install_dir string
+function M.check_outdated_primary_package(receipt, install_dir)
+    if receipt.primary_source.type ~= "gem" then
+        return Result.failure "Receipt does not have a primary source of type gem"
+    end
+    return spawn.gem({ "outdated", cwd = install_dir, env = M.env(install_dir) }):map_catching(function(result)
+        ---@type string[]
+        local lines = vim.split(result.stdout, "\n")
+        local outdated_gems = vim.tbl_map(M.parse_outdated_gem, vim.tbl_filter(not_empty, lines))
+
+        local outdated_gem = _.find_first(function(gem)
+            return gem.name == receipt.primary_source.package and gem.current_version ~= gem.latest_version
+        end, outdated_gems)
+
+        return Optional.of_nilable(outdated_gem)
+            :map(function(gem)
+                return {
+                    name = receipt.primary_source.package,
+                    current_version = assert(gem.current_version),
+                    latest_version = assert(gem.latest_version),
+                }
+            end)
+            :or_else_throw "Primary package is not outdated."
+    end)
+end
+
+---@async
+---@param receipt InstallReceipt
+---@param install_dir string
+function M.get_installed_primary_package_version(receipt, install_dir)
+    return spawn
+        .gem({
+            "list",
+            cwd = install_dir,
+            env = M.env(install_dir),
+        })
+        :map_catching(function(result)
+            local gems = M.parse_gem_list_output(result.stdout)
+            return Optional.of_nilable(gems[receipt.primary_source.package])
+                :or_else_throw "Failed to find gem package version."
+        end)
+end
+
+---@param install_dir string
+function M.env(install_dir)
+    return {
+        GEM_HOME = install_dir,
+        GEM_PATH = install_dir,
+        PATH = process.extend_path { path.concat { install_dir, "bin" } },
+    }
+end
+
+return M