1 files changed, 138 insertions, 0 deletions
diff --git a/Omni/Agent/Git.hs b/Omni/Agent/Git.hs
new file mode 100644
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+++ b/Omni/Agent/Git.hs
@@ -0,0 +1,138 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+
+-- | Git operations for the agent.
+--
+-- : out omni-agent-git
+-- : dep temporary
+module Omni.Agent.Git
+  ( checkout,
+    main,
+    test,
+  )
+where
+
+import Alpha
+import qualified Data.Text as Text
+import qualified Omni.Log as Log
+import Omni.Test ((@=?))
+import qualified Omni.Test as Test
+import qualified System.Directory as Directory
+import qualified System.Exit as Exit
+import qualified System.IO.Temp as Temp
+import qualified System.Process as Process
+
+main :: IO ()
+main = Test.run test
+
+test :: Test.Tree
+test =
+  Test.group
+    "Omni.Agent.Git"
+    [ Test.unit "checkout works" <| do
+        Temp.withSystemTempDirectory "omni-agent-git-test" <| \tmpDir -> do
+          let repo = tmpDir <> "/repo"
+          Directory.createDirectory repo
+          -- init repo
+          git repo ["init"]
+          git repo ["branch", "-m", "master"]
+          git repo ["config", "user.email", "you@example.com"]
+          git repo ["config", "user.name", "Your Name"]
+
+          -- commit A
+          writeFile (repo <> "/a.txt") "A"
+          git repo ["add", "a.txt"]
+          git repo ["commit", "-m", "A"]
+          shaA <- getSha repo "HEAD"
+
+          -- create branch dev
+          git repo ["checkout", "-b", "dev"]
+
+          -- commit B
+          writeFile (repo <> "/b.txt") "B"
+          git repo ["add", "b.txt"]
+          git repo ["commit", "-m", "B"]
+          shaB <- getSha repo "HEAD"
+
+          -- switch back to master
+          git repo ["checkout", "master"]
+
+          -- Test 1: checkout dev
+          checkout repo "dev"
+          current <- getSha repo "HEAD"
+          shaB @=? current
+
+          -- Test 2: checkout master
+          checkout repo "master"
+          current' <- getSha repo "HEAD"
+          shaA @=? current'
+
+          -- Test 3: dirty state
+          writeFile (repo <> "/a.txt") "DIRTY"
+          checkout repo "dev"
+          current'' <- getSha repo "HEAD"
+          shaB @=? current''
+          -- Verify dirty file is gone/overwritten (b.txt should exist, a.txt should be A from master? No, a.txt is in A and B)
+          -- Wait, in dev, a.txt is "A".
+          content <- readFile (repo <> "/a.txt")
+          "A" @=? content
+
+          -- Test 4: untracked file
+          writeFile (repo <> "/untracked.txt") "DELETE ME"
+          checkout repo "master"
+          exists <- Directory.doesFileExist (repo <> "/untracked.txt")
+          False @=? exists
+    ]
+
+getSha :: FilePath -> String -> IO String
+getSha dir ref = do
+  let cmd = (Process.proc "git" ["rev-parse", ref]) {Process.cwd = Just dir}
+  (code, out, _) <- Process.readCreateProcessWithExitCode cmd ""
+  case code of
+    Exit.ExitSuccess -> pure <| strip out
+    _ -> panic "getSha failed"
+
+-- | Checkout a specific ref (SHA, branch, tag) in the given repository path.
+-- This function ensures the repository is in the correct state by:
+-- 1. Fetching all updates
+-- 2. Checking out the ref (forcing overwrites of local changes)
+-- 3. Resetting hard to the ref (to ensure clean state)
+-- 4. Cleaning untracked files
+-- 5. Updating submodules
+checkout :: FilePath -> Text -> IO ()
+checkout repoPath ref = do
+  let r = Text.unpack ref
+
+  Log.info ["git", "checkout", ref, "in", Text.pack repoPath]
+
+  -- Fetch all refs to ensure we have the target
+  git repoPath ["fetch", "--all", "--tags"]
+
+  -- Checkout the ref, discarding local changes
+  git repoPath ["checkout", "--force", r]
+
+  -- Reset hard to ensure we are exactly at the target state
+  git repoPath ["reset", "--hard", r]
+
+  -- Remove untracked files and directories
+  git repoPath ["clean", "-fdx"]
+
+  -- Update submodules
+  git repoPath ["submodule", "update", "--init", "--recursive"]
+
+  Log.good ["git", "checkout", "complete"]
+  Log.br
+
+-- | Run a git command in the given directory.
+git :: FilePath -> [String] -> IO ()
+git dir args = do
+  let cmd = (Process.proc "git" args) {Process.cwd = Just dir}
+  (exitCode, out, err) <- Process.readCreateProcessWithExitCode cmd ""
+  case exitCode of
+    Exit.ExitSuccess -> pure ()
+    Exit.ExitFailure code -> do
+      Log.fail ["git command failed", Text.pack (show args), "code: " <> show code]
+      Log.info [Text.pack out]
+      Log.info [Text.pack err]
+      Log.br
+      panic <| "git command failed: git " <> show args