package changelog

import (
	"os"
	"os/exec"
	"path/filepath"
	"reflect"
	"strings"
	"testing"

	"github.com/carlosframework/platform/internal/docsite"
)

// scratchRepo builds a small history with every shape main has had:
//
//	v0.1.0: a root commit adding docs/site/cli.md
//	        a direct commit
//	        an Amadan squash of branch "feat/x", whose own two commits
//	        survive at refs/amadan/closed/feat/x
//	        a GitHub merge of branch "gh-branch"
//	v0.2.0
type scratch struct {
	t   *testing.T
	dir string
	n   int
}

func (s *scratch) git(env []string, args ...string) string {
	s.t.Helper()
	cmd := exec.Command("git", append([]string{"-C", s.dir}, args...)...)
	cmd.Env = append(os.Environ(),
		"GIT_CONFIG_GLOBAL=/dev/null", "GIT_CONFIG_SYSTEM=/dev/null",
		"GIT_AUTHOR_NAME=Paul Campbell", "GIT_AUTHOR_EMAIL=paul@tito.io",
		"GIT_COMMITTER_NAME=Paul Campbell", "GIT_COMMITTER_EMAIL=paul@tito.io")
	cmd.Env = append(cmd.Env, env...)
	out, err := cmd.CombinedOutput()
	if err != nil {
		s.t.Fatalf("git %v: %v\n%s", args, err, out)
	}
	return strings.TrimSpace(string(out))
}

func (s *scratch) commit(author []string, msg, file, body string) string {
	s.t.Helper()
	s.n++
	date := []string{
		"GIT_AUTHOR_DATE=2026-09-0" + string(rune('0'+s.n)) + "T12:00:00Z",
		"GIT_COMMITTER_DATE=2026-09-0" + string(rune('0'+s.n)) + "T12:00:00Z",
	}
	if err := os.MkdirAll(filepath.Dir(filepath.Join(s.dir, file)), 0o755); err != nil {
		s.t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(s.dir, file), []byte(body), 0o644); err != nil {
		s.t.Fatal(err)
	}
	s.git(nil, "add", file)
	s.git(append(author, date...), "commit", "-q", "-m", msg)
	return s.git(nil, "rev-parse", "HEAD")
}

var asClaude = []string{"GIT_AUTHOR_NAME=claude", "GIT_AUTHOR_EMAIL=claude~paul@keymail.dev"}

func newScratch(t *testing.T) *scratch {
	s := &scratch{t: t, dir: t.TempDir()}
	s.git(nil, "init", "-q", "-b", "main")
	s.commit(nil, "root", "docs/site/cli.md", "# The CLI\n\n### carlos db\n\ntext\n")
	s.git(nil, "tag", "-a", "v0.1.0", "-m", "carlos v0.1.0")
	s.commit(nil, "a direct commit\n\nCo-Authored-By: Claude <noreply@anthropic.com>", "a.txt", "a")

	s.git(nil, "checkout", "-q", "-b", "feat/x")
	s.commit(asClaude, "x one", "x.txt", "1")
	s.commit(asClaude, "x two (#7)", "docs/site/cli.md", "# The CLI\n\n### carlos db\n\ntext\nmore\n")
	s.git(nil, "update-ref", "refs/amadan/closed/feat/x", "HEAD")
	s.git(nil, "checkout", "-q", "main")
	s.git(nil, "merge", "-q", "--squash", "feat/x")
	s.git(append(asClaude, "GIT_COMMITTER_DATE=2026-09-08T12:00:00Z", "GIT_AUTHOR_DATE=2026-09-08T12:00:00Z"),
		"commit", "-q", "-m", "x: the feature\n\nSquashed from feat/x into main.")

	s.git(nil, "checkout", "-q", "-b", "gh-branch")
	s.commit([]string{"GIT_AUTHOR_NAME=Bill Horsman", "GIT_AUTHOR_EMAIL=bill@keymail.dev"}, "gh work", "g.txt", "g")
	s.git(nil, "checkout", "-q", "main")
	s.git([]string{"GIT_AUTHOR_NAME=GitHub", "GIT_AUTHOR_EMAIL=noreply@github.com", "GIT_COMMITTER_DATE=2026-09-09T12:00:00Z"},
		"merge", "-q", "--no-ff", "gh-branch", "-m", "Merge pull request #3 from carlosframework/gh-branch")
	s.git(nil, "tag", "v0.2.0")
	return s
}

func TestExecGitEndToEnd(t *testing.T) {
	s := newScratch(t)
	g, err := NewExecGit(s.dir)
	if err != nil {
		t.Fatal(err)
	}
	tags, err := g.Tags()
	if err != nil || len(tags) != 2 {
		t.Fatalf("tags = %+v, %v", tags, err)
	}
	if _, _, ok := g.Tombstone("feat/x"); !ok {
		t.Fatal("tombstone feat/x not found")
	}

	rel := fakeReleases{
		"v0.1.0": "First release.\n",
		"v0.2.0": "carlos v0.2.0 (platform x, 2026-09-09)\n\n- **The feature.** `carlos db pull`.\n",
	}
	disc := &fakeDiscussions{byID: map[int]Discussion{7: {ID: 7, Title: "seven", State: "open", Created: 1}}}
	site := testSite(t)
	site.BySlug["cli"] = docsite.Parse("cli", "# The CLI\n\n### carlos db\n\ntext\nmore\n")
	c, err := Build(Sources{g, rel, disc}, testPeople, Links{"v0.2.0": {"The feature.": {"feat/x"}}}, site)
	if err != nil {
		t.Fatal(err)
	}
	if len(c.Releases) != 2 || c.Releases[0].Tag != "v0.2.0" {
		t.Fatalf("releases = %+v", c.Releases)
	}
	ch := c.Releases[0].Changes
	if len(ch) != 3 {
		t.Fatalf("v0.2.0 changes = %+v", ch)
	}
	merge, squash, direct := ch[0], ch[1], ch[2]

	if merge.Branch != "gh-branch" || merge.BranchURL != "" || merge.Commits != 1 || merge.Subject != "gh work" ||
		!reflect.DeepEqual(merge.Credit, []Credit{{Person: "Bill Horsman"}}) {
		t.Errorf("merge = %+v", merge)
	}
	if squash.Branch != "feat/x" || squash.BranchURL != RepoURL+"/-/branch/feat%2Fx" || squash.Commits != 2 {
		t.Errorf("squash = %+v", squash)
	}
	if !reflect.DeepEqual(squash.Credit, []Credit{{Person: "Paul Campbell", Agents: []string{"claude"}}}) {
		t.Errorf("squash credit = %+v", squash.Credit)
	}
	if len(squash.Discussions) != 1 || squash.Discussions[0].ID != 7 {
		t.Errorf("squash discussions = %+v", squash.Discussions)
	}
	if !reflect.DeepEqual(squash.Docs, []string{"/docs/cli#carlos-db"}) {
		t.Errorf("squash docs = %v", squash.Docs)
	}
	if direct.Branch != "" || !reflect.DeepEqual(direct.Credit, []Credit{{Person: "Paul Campbell", Agents: []string{"claude"}}}) {
		t.Errorf("direct = %+v", direct)
	}

	first := c.Releases[1]
	if first.Tag != "v0.1.0" || !first.Published || len(first.Changes) != 1 || first.Changes[0].Subject != "root" {
		t.Fatalf("v0.1.0 = %+v", first)
	}
	if !reflect.DeepEqual(first.Changes[0].Docs, []string{"/docs/cli#carlos-db"}) {
		t.Errorf("root docs = %v", first.Changes[0].Docs)
	}
}