#!/usr/bin/env bash
# Regression harness for `git-credential-mosaic` — per-agent Gitea identity
# resolution (Gate-16 author≠reviewer separation).
#
# Covers:
#   1. Identity resolution priority: MOSAIC_GIT_IDENTITY env > git config
#      mosaic.gitIdentity (per-worktree) > git-supplied username.
#   2. Correct per-slot token file path chosen per host
#      (gitea-usc-<id>.token vs gitea-mosaicstack-<id>.token).
#   3. Per-slot token present -> emits that identity + token.
#   4. Per-slot token absent -> falls back to the shared account
#      (backward-compat / no-op for hosts without per-slot tokens).
#   5. Unknown/unrelated host -> exits 0 with no output (passthrough).
#
# Uses stubbed token files under a fake HOME + a real (throwaway) git repo.
# NEVER reads real secrets or touches the real ~/.config/mosaic/secrets.

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/git-credential-mosaic}"
FAKE_HOME="$WORK_DIR/home"
REPO_DIR="$WORK_DIR/repo"
# Mirror the real deployed layout (~/.config/mosaic/tools/{git,_lib}/) under the
# fake HOME: git-credential-mosaic resolves its credentials.sh sibling via a
# script-relative path (BASH_SOURCE), so the copy must live next to a stubbed
# _lib/credentials.sh, not the real one, to keep this test hermetic.
HELPER="$FAKE_HOME/.config/mosaic/tools/git/git-credential-mosaic"

rm -rf "$WORK_DIR"
mkdir -p "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens" \
         "$FAKE_HOME/.config/mosaic/tools/git" \
         "$FAKE_HOME/.config/mosaic/tools/_lib" \
         "$REPO_DIR"

cp "$SCRIPT_DIR/git-credential-mosaic" "$HELPER"
chmod +x "$HELPER"

git -C "$REPO_DIR" init -q
git -C "$REPO_DIR" config user.email "test@example.invalid"
git -C "$REPO_DIR" config user.name "Test"

# Fake shared-account credential loader — stands in for
# tools/_lib/credentials.sh's load_credentials(), scoped to this test only.
cat > "$FAKE_HOME/.config/mosaic/tools/_lib/credentials.sh" <<'SH'
load_credentials() {
  case "$1" in
    gitea-mosaicstack) GITEA_URL="https://git.mosaicstack.dev"; GITEA_TOKEN="shared-mosaicstack-token"; export GITEA_URL GITEA_TOKEN; return 0 ;;
    gitea-usc)         GITEA_URL="https://git.uscllc.com"; GITEA_TOKEN="shared-usc-token"; export GITEA_URL GITEA_TOKEN; return 0 ;;
    *) return 1 ;;
  esac
}
SH

fail=0
assert_eq() {
  local desc="$1" expected="$2" actual="$3"
  if [[ "$expected" != "$actual" ]]; then
    echo "FAIL: $desc — expected '$expected', got '$actual'" >&2
    fail=1
  fi
}

# Feed "host=<h>\nusername=<u>\n\n" on stdin (mirrors git's credential protocol)
# and run the helper with the fake HOME, inside REPO_DIR (so `git config
# mosaic.gitIdentity` resolves per-worktree), plus any extra env passed in $@.
run_helper() {
  local host="$1" username_in="$2"; shift 2
  (
    cd "$REPO_DIR"
    env -i HOME="$FAKE_HOME" PATH="$PATH" "$@" bash "$HELPER" get <<EOF
host=$host
username=$username_in

EOF
  )
}

# ---------------------------------------------------------------------------
# 1. No identity resolvable anywhere, no per-slot token -> shared fallback
#    (backward-compat: unchanged behavior when nothing is configured).
# ---------------------------------------------------------------------------
git -C "$REPO_DIR" config --unset mosaic.gitIdentity 2>/dev/null || true
out=$(run_helper "git.mosaicstack.dev" "")
assert_eq "shared fallback: username" "username=git" "$(echo "$out" | grep '^username=')"
assert_eq "shared fallback: password" "password=shared-mosaicstack-token" "$(echo "$out" | grep '^password=')"

# ---------------------------------------------------------------------------
# 2. git-supplied username resolves to an identity WITH a per-slot token ->
#    that identity + token wins over the shared account.
# ---------------------------------------------------------------------------
echo -n "agentA-mosaicstack-token" > "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-mosaicstack-agentA.token"
out=$(run_helper "git.mosaicstack.dev" "agentA")
assert_eq "username-resolved identity: username" "username=agentA" "$(echo "$out" | grep '^username=')"
assert_eq "username-resolved identity: password" "password=agentA-mosaicstack-token" "$(echo "$out" | grep '^password=')"

# ---------------------------------------------------------------------------
# 3. git config mosaic.gitIdentity (per-worktree) beats git-supplied username.
# ---------------------------------------------------------------------------
echo -n "agentB-mosaicstack-token" > "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-mosaicstack-agentB.token"
git -C "$REPO_DIR" config mosaic.gitIdentity agentB
out=$(run_helper "git.mosaicstack.dev" "agentA")
assert_eq "git-config beats username: username" "username=agentB" "$(echo "$out" | grep '^username=')"
assert_eq "git-config beats username: password" "password=agentB-mosaicstack-token" "$(echo "$out" | grep '^password=')"

# ---------------------------------------------------------------------------
# 4. MOSAIC_GIT_IDENTITY env beats git config mosaic.gitIdentity.
# ---------------------------------------------------------------------------
echo -n "agentC-mosaicstack-token" > "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-mosaicstack-agentC.token"
out=$(run_helper "git.mosaicstack.dev" "agentA" MOSAIC_GIT_IDENTITY=agentC)
assert_eq "env beats git-config: username" "username=agentC" "$(echo "$out" | grep '^username=')"
assert_eq "env beats git-config: password" "password=agentC-mosaicstack-token" "$(echo "$out" | grep '^password=')"
git -C "$REPO_DIR" config --unset mosaic.gitIdentity

# ---------------------------------------------------------------------------
# 5. Identity resolves, but no matching per-slot token file -> falls back to
#    the shared account (per-agent identity is opt-in, not a hard requirement).
# ---------------------------------------------------------------------------
out=$(run_helper "git.mosaicstack.dev" "no-such-agent")
assert_eq "no per-slot token: username" "username=git" "$(echo "$out" | grep '^username=')"
assert_eq "no per-slot token: password" "password=shared-mosaicstack-token" "$(echo "$out" | grep '^password=')"

# ---------------------------------------------------------------------------
# 6. Correct per-slot token PATH is chosen per host: same agent id, different
#    host prefix (gitea-usc- vs gitea-mosaicstack-).
# ---------------------------------------------------------------------------
echo -n "agentD-usc-token" > "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-usc-agentD.token"
out=$(run_helper "git.uscllc.com" "agentD")
assert_eq "host-scoped token path (usc): username" "username=agentD" "$(echo "$out" | grep '^username=')"
assert_eq "host-scoped token path (usc): password" "password=agentD-usc-token" "$(echo "$out" | grep '^password=')"
# agentD has NO mosaicstack token -> must fall back to shared mosaicstack, not
# leak the usc token across hosts.
out=$(run_helper "git.mosaicstack.dev" "agentD")
assert_eq "host-scoped token path (cross-host must not leak): username" "username=git" "$(echo "$out" | grep '^username=')"
assert_eq "host-scoped token path (cross-host must not leak): password" "password=shared-mosaicstack-token" "$(echo "$out" | grep '^password=')"

# ---------------------------------------------------------------------------
# 7. Unrelated/unknown host -> exit 0, no output (passthrough for non-Gitea
#    remotes, e.g. github.com via a different credential helper).
# ---------------------------------------------------------------------------
out=$(run_helper "github.com" "agentA")
assert_eq "unknown host: no output" "" "$out"

# ---------------------------------------------------------------------------
# 8. Non-"get" verb (store/erase) -> exit 0, no output (git-credential
#    protocol: this helper only implements get).
# ---------------------------------------------------------------------------
store_out=$(cd "$REPO_DIR" && env -i HOME="$FAKE_HOME" PATH="$PATH" bash "$HELPER" store <<EOF
host=git.mosaicstack.dev
username=agentA
password=whatever

EOF
)
assert_eq "store verb: no output" "" "$store_out"

if [[ "$fail" -eq 0 ]]; then
  echo "git-credential-mosaic identity resolution regression passed"
fi

exit "$fail"