package server

import (
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
	"testing"
)

// Guards the version derivation that stamps every build.
//
// These assertions used to be impossible to run. The derivation lived inline
// in release.yml, which triggers only on `main` and on tags — so a mistake in
// it could not surface until a release was already under way, and its failure
// mode is silence: a version nobody can compare looks exactly like being up to
// date, and nobody reports an update they were never offered.
//
// Moving it to ci/version.sh made it executable, so this runs on every push
// that touches the release machinery. That is the whole point of the file; the
// specific assertions below matter less than the fact that they run at all.
//
// The tests EXECUTE the script rather than asserting on its text, so they
// break when the behaviour changes rather than when the wording does.

// highestOldSchemeCode is the largest versionCode ever shipped under the
// retired commit-count scheme (v2026.09.09 shipped 1895). Every code the new
// scheme emits must clear it, or Android would refuse the upgrade as a
// downgrade and the update channel would be a one-way door.
const highestOldSchemeCode = 1895

func repoRoot(t *testing.T) string {
	t.Helper()
	dir, err := os.Getwd()
	if err != nil {
		t.Fatal(err)
	}
	for {
		if _, err := os.Stat(filepath.Join(dir, "go.mod")); err == nil {
			return dir
		}
		parent := filepath.Dir(dir)
		if parent == dir {
			t.Fatalf("no go.mod above %s", dir)
		}
		dir = parent
	}
}

// runVersion executes ci/version.sh with both clocks pinned, so the result is
// deterministic. Returns the parsed KEY=VALUE output.
func runVersion(t *testing.T, commitEpoch, nowEpoch string) map[string]string {
	t.Helper()
	out, err := versionScript(t, commitEpoch, nowEpoch)
	if err != nil {
		t.Fatalf("ci/version.sh failed: %v\n%s", err, out)
	}
	parsed := map[string]string{}
	for _, line := range strings.Split(strings.TrimSpace(out), "\n") {
		if k, v, ok := strings.Cut(line, "="); ok {
			parsed[k] = v
		}
	}
	return parsed
}

func versionScript(t *testing.T, commitEpoch, nowEpoch string) (string, error) {
	t.Helper()
	root := repoRoot(t)
	cmd := exec.Command(filepath.Join(root, "ci", "version.sh"))
	cmd.Dir = root
	cmd.Env = append(os.Environ(),
		"MINSTREL_COMMIT_EPOCH="+commitEpoch,
		"MINSTREL_NOW_EPOCH="+nowEpoch,
	)
	out, err := cmd.CombinedOutput()
	return string(out), err
}

func TestVersionName_IsCommitTimeToTheMinute(t *testing.T) {
	// 2025-09-09T18:48:56Z
	got := runVersion(t, "1757443736", "1789000920")
	if want := "2025.09.09.1848"; got["name"] != want {
		t.Errorf("name = %q, want %q", got["name"], want)
	}
}

// HHMM is the segment most likely to be silently mangled, and it only bites
// for about a tenth of the day — a build just after midnight must emit "0042",
// never "42". A stripped leading zero shifts the segment by two orders of
// magnitude and reverses comparisons against every other build that day.
func TestVersionName_PadsTheMinuteSegment(t *testing.T) {
	// 2026-09-10T00:42:00Z
	got := runVersion(t, "1789000920", "1789000920")
	if want := "2026.09.10.0042"; got["name"] != want {
		t.Errorf("name = %q, want %q — leading zero lost?", got["name"], want)
	}
}

func TestVersionName_DerivesFromCommitNotBuildClock(t *testing.T) {
	// Same commit, two different build clocks: the NAME must not move, or a
	// dev build and a main build of one commit would report different strings
	// and the channel field would stop being the only thing separating them.
	a := runVersion(t, "1757443736", "1789000920")
	b := runVersion(t, "1757443736", "1789500000")
	if a["name"] != b["name"] {
		t.Errorf("name moved with the build clock: %q vs %q", a["name"], b["name"])
	}
	if a["code"] == b["code"] {
		t.Errorf("code did NOT move with the build clock (%q) — it is not build-derived", a["code"])
	}
}

func TestVersionCode_IsMinutesSince2020AndClearsTheOldScheme(t *testing.T) {
	got := runVersion(t, "1789000920", "1789000920")
	code, err := strconv.Atoi(got["code"])
	if err != nil {
		t.Fatalf("code %q is not an integer: %v", got["code"], err)
	}
	if want := (1789000920 - 1577836800) / 60; code != want {
		t.Errorf("code = %d, want %d", code, want)
	}
	if code <= highestOldSchemeCode {
		t.Errorf("code %d does not clear the retired commit-count scheme (%d) — "+
			"Android would refuse the upgrade as a downgrade", code, highestOldSchemeCode)
	}
	if int64(code) > 2147483647 {
		t.Errorf("code %d overflows versionCode's int32 ceiling", code)
	}
}

// The tag is not chosen, it is the name with a `v`. Anything else reintroduces
// the mismatch between what a tag claims and what the artifact reports.
func TestTag_IsTheNameWithAPrefix(t *testing.T) {
	got := runVersion(t, "1757443736", "1789000920")
	if want := "v" + got["name"]; got["tag"] != want {
		t.Errorf("tag = %q, want %q", got["tag"], want)
	}
}

// A guard that cannot fail is worse than no guard. These prove the script
// rejects the shapes it claims to reject, rather than emitting something
// plausible and letting it ship.
func TestVersionScript_RejectsUnusableClocks(t *testing.T) {
	for _, tc := range []struct{ name, commit, now string }{
		{"unreadable commit timestamp", "notanumber", "1789000920"},
		{"non-numeric build clock", "1789000920", "abc"},
		{"build clock before 2020", "1789000920", "1000000000"},
	} {
		t.Run(tc.name, func(t *testing.T) {
			out, err := versionScript(t, tc.commit, tc.now)
			if err == nil {
				t.Errorf("script succeeded on %s, output: %s", tc.name, out)
			}
		})
	}
}

// Pins the wiring, not the formula: if release.yml stops calling the script,
// every assertion above keeps passing while the thing that actually ships goes
// unguarded again. That silent decoupling is the specific regression here.
func TestReleaseWorkflow_UsesTheSharedDerivation(t *testing.T) {
	body, err := os.ReadFile(filepath.Join(repoRoot(t), ".gitea", "workflows", "release.yml"))
	if err != nil {
		t.Fatal(err)
	}
	yaml := string(body)

	if !strings.Contains(yaml, "ci/version.sh") {
		t.Error("release.yml no longer calls ci/version.sh — the derivation has drifted out of test coverage")
	}
	// The retired scheme, which must not come back. A presence check is safe
	// against prose; the historical note in that file names the old formula
	// only in comments, so match the executable form.
	if strings.Contains(yaml, "$(git rev-list --count") {
		t.Error("release.yml derives a commit count again — that is not monotonic across branches")
	}
}

// devArm returns the branch of "Compute image tags" that handles refs/heads/dev.
func devArm(t *testing.T, yaml string) string {
	t.Helper()
	const marker = `elif [[ "${GITHUB_REF}" == "refs/heads/dev" ]]; then`
	i := strings.Index(yaml, marker)
	if i < 0 {
		t.Fatal("no refs/heads/dev arm in Compute image tags — the dev channel is not wired")
	}
	rest := yaml[i+len(marker):]
	if j := strings.Index(rest, "\n          else"); j >= 0 {
		return rest[:j]
	}
	return rest
}

// The worst regression this wiring can produce: a dev push that also moves
// :latest would ship untested code to every stable operator, silently, on the
// next pull. Nothing else in the suite would notice — the build stays green
// and the image is valid, it is simply the wrong audience.
func TestDevChannel_PublishesDevAloneAndNeverLatest(t *testing.T) {
	body, err := os.ReadFile(filepath.Join(repoRoot(t), ".gitea", "workflows", "release.yml"))
	if err != nil {
		t.Fatal(err)
	}
	arm := devArm(t, string(body))

	if !strings.Contains(arm, "${IMAGE}:dev") {
		t.Errorf("dev arm does not publish :dev\n%s", arm)
	}
	if strings.Contains(arm, ":latest") {
		t.Errorf("dev arm moves :latest — that ships dev code to every stable operator\n%s", arm)
	}
	// Rule 145: a rolling channel gets no commit-addressable tag.
	if strings.Contains(arm, "GITHUB_SHA") {
		t.Errorf("dev arm publishes a per-commit tag; a rolling channel should not\n%s", arm)
	}
}

// The two bundling paths must stay mutually exclusive. If the rebundle step's
// condition were relaxed back to "not a tag", a dev push would run BOTH: stage
// its freshly-built APK, then overwrite it with the previous release's. The
// image would still build and the sidecar would still parse — it would just
// quietly serve stale art to the channel whose whole job is being current.
func TestDevChannel_RebundlePathIsMainOnly(t *testing.T) {
	body, err := os.ReadFile(filepath.Join(repoRoot(t), ".gitea", "workflows", "release.yml"))
	if err != nil {
		t.Fatal(err)
	}
	yaml := string(body)

	i := strings.Index(yaml, "- name: Bundle latest release APK")
	if i < 0 {
		t.Fatal("no 'Bundle latest release APK' step")
	}
	step := yaml[i:]
	if j := strings.Index(step, "\n      - name:"); j >= 0 {
		step = step[:j]
	}
	if !strings.Contains(step, "github.ref == 'refs/heads/main'") {
		t.Errorf("the rebundle step is not gated to main; a dev push would overwrite its own APK\n%s", step)
	}
}