package ciscript_test

import (
	"maps"
	"os"
	"os/exec"
	"path/filepath"
	"slices"
	"strings"
	"testing"

	"github.com/stretchr/testify/require"
	"gopkg.in/yaml.v3"
)

const (
	// supersededDesc is the description script/ci-mark-superseded
	// writes, and the one an earlier revision of it wrote alongside a
	// `skipped` state.
	supersededDesc = "Superseded by a newer commit; never tested"

	// liveContext is the commit-status context Gitea uses for this
	// repository's runs, as seen in its API. The script derives it from
	// the workflow and job names rather than hardcoding it; the
	// derivation is checked against this value below.
	liveContext = "check / check (push)"

	scriptPath = "../../script/ci-mark-superseded"
	workflow   = "../../.gitea/workflows/check.yml"

	// failure is the only state that neither folds into a combined
	// `success` (as `skipped` does) nor blocks the commit forever (as
	// `pending` does).
	failure = "failure"
)

// repo is a throwaway git history: parent is the commit a run would be
// cancelled on, head the commit that superseded it.
type repo struct {
	dir    string
	head   string
	parent string
}

// scriptEnv is the run identity the Gitea runner exports and the script
// builds its context string from.
type scriptEnv struct {
	workflow string
	job      string
	event    string
}

func defaultEnv() scriptEnv {
	return scriptEnv{workflow: "check", job: "check", event: "push"}
}

func cancelled() commitStatus {
	return commitStatus{
		Context:     liveContext,
		Status:      failure,
		Description: "Has been cancelled",
	}
}

func running() commitStatus {
	return commitStatus{
		Context:     liveContext,
		Status:      "pending",
		Description: "Has started running",
	}
}

func TestMarkSuperseded(t *testing.T) {
	t.Parallel()

	cases := map[string]struct {
		parent   commitStatus
		wantMark bool
	}{
		"a cancelled run is marked": {
			parent:   cancelled(),
			wantMark: true,
		},
		"a laundered skipped status is marked": {
			parent: commitStatus{
				Context:     liveContext,
				Status:      "skipped",
				Description: supersededDesc,
			},
			wantMark: true,
		},
		"a genuine failure is left alone": {
			parent: commitStatus{
				Context:     liveContext,
				Status:      failure,
				Description: "Failing after 3m1s",
			},
			wantMark: false,
		},
		"a passing run is left alone": {
			parent: commitStatus{
				Context:     liveContext,
				Status:      "success",
				Description: "Successful in 2m52s",
			},
			wantMark: false,
		},
		"another context is left alone": {
			parent: commitStatus{
				Context:     "other / other (push)",
				Status:      failure,
				Description: "Has been cancelled",
			},
			wantMark: false,
		},
	}

	for name, tc := range cases {
		t.Run(name, func(t *testing.T) {
			t.Parallel()
			requireTools(t)

			history := newRepo(t)
			fake, api := newFakeGitea(t)
			fake.setStatus(history.head, running())
			fake.setStatus(history.parent, tc.parent)

			out, err := runScript(t, history, api, defaultEnv())
			require.NoError(t, err, out)

			posted := fake.postedFor(history.parent)
			if !tc.wantMark {
				require.Empty(t, posted)

				return
			}

			require.Equal(t, []postedStatus{{
				Context: liveContext,
				// Not `skipped`: Gitea's combined status folds
				// that into `success`, which is what made a
				// never-tested commit read green.
				State:       failure,
				Description: supersededDesc,
			}}, posted)
		})
	}
}

// A second run must not rewrite what the first one wrote, or every
// later push would post a duplicate status.
func TestMarkSupersededIsIdempotent(t *testing.T) {
	t.Parallel()
	requireTools(t)

	history := newRepo(t)
	fake, api := newFakeGitea(t)
	fake.setStatus(history.head, running())
	fake.setStatus(history.parent, cancelled())

	for range 2 {
		out, err := runScript(t, history, api, defaultEnv())
		require.NoError(t, err, out)
	}

	require.Len(t, fake.postedFor(history.parent), 1)
}

// Renaming the workflow or the job changes the context string Gitea
// uses. The script must say so instead of quietly matching nothing.
func TestMarkSupersededRejectsAnUnknownContext(t *testing.T) {
	t.Parallel()
	requireTools(t)

	history := newRepo(t)
	fake, api := newFakeGitea(t)
	fake.setStatus(history.head, running())
	fake.setStatus(history.parent, cancelled())

	env := defaultEnv()
	env.job = "renamed"

	out, err := runScript(t, history, api, env)
	require.Error(t, err)
	require.Contains(t, out, "renamed")
	require.Contains(t, out, liveContext)
	require.Empty(t, fake.postedFor(history.parent))
}

// The derived context must equal the one Gitea actually uses, which is
// built from the same workflow and job names.
func TestDerivedContextMatchesGitea(t *testing.T) {
	t.Parallel()
	requireTools(t)

	name, job := workflowIdentity(t)

	history := newRepo(t)
	fake, api := newFakeGitea(t)
	fake.setStatus(history.head, running())
	fake.setStatus(history.parent, cancelled())

	out, err := runScript(t, history, api, scriptEnv{
		workflow: name,
		job:      job,
		event:    "push",
	})
	require.NoError(t, err, out)

	posted := fake.postedFor(history.parent)
	require.Len(t, posted, 1)
	require.Equal(t, liveContext, posted[0].Context)
}

// workflowIdentity reads the workflow name and its single job id out of
// the checked-in workflow file.
func workflowIdentity(t *testing.T) (string, string) {
	t.Helper()

	raw, err := os.ReadFile(workflow)
	require.NoError(t, err)

	var parsed struct {
		Name string         `yaml:"name"`
		Jobs map[string]any `yaml:"jobs"`
	}

	require.NoError(t, yaml.Unmarshal(raw, &parsed))

	jobs := slices.Collect(maps.Keys(parsed.Jobs))
	require.Len(t, jobs, 1)

	return parsed.Name, jobs[0]
}

func runScript(
	t *testing.T, history repo, api string, env scriptEnv,
) (string, error) {
	t.Helper()

	script, err := filepath.Abs(scriptPath)
	require.NoError(t, err)

	//nolint:gosec // fixed argv, repo-local script under test
	cmd := exec.CommandContext(t.Context(), "sh", script)
	cmd.Dir = history.dir
	cmd.Env = append(os.Environ(),
		"GITHUB_API_URL="+api,
		"GITHUB_REPOSITORY=sneak/webhooker",
		"GITHUB_SHA="+history.head,
		"GITHUB_WORKFLOW="+env.workflow,
		"GITHUB_JOB="+env.job,
		"GITHUB_EVENT_NAME="+env.event,
		"GITEA_TOKEN=test-token",
	)

	out, err := cmd.CombinedOutput()

	return string(out), err
}

func newRepo(t *testing.T) repo {
	t.Helper()

	dir := t.TempDir()

	git := func(args ...string) string {
		//nolint:gosec // fixed argv, arguments are test constants
		cmd := exec.CommandContext(t.Context(), "git", args...)
		cmd.Dir = dir

		out, err := cmd.CombinedOutput()
		require.NoError(t, err, string(out))

		return strings.TrimSpace(string(out))
	}

	commit := func(message string) string {
		git(
			"-c", "user.email=ci@example.invalid",
			"-c", "user.name=ci",
			"-c", "commit.gpgsign=false",
			"commit", "-q", "--allow-empty", "-m", message,
		)

		return git("rev-parse", "HEAD")
	}

	git("init", "-q", "-b", "main")

	parent := commit("parent")
	head := commit("head")

	return repo{dir: dir, head: head, parent: parent}
}

func requireTools(t *testing.T) {
	t.Helper()

	for _, tool := range []string{"sh", "git", "curl", "jq"} {
		_, err := exec.LookPath(tool)
		if err != nil {
			t.Skipf("%s is not installed: %v", tool, err)
		}
	}
}