package main

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

func TestApplyChangesRewritesMetadata(t *testing.T) {
	repo := t.TempDir()

	run := func(args ...string) string {
		t.Helper()
		cmd := exec.Command("git", append([]string{"-C", repo}, args...)...)
		out, err := cmd.CombinedOutput()
		if err != nil {
			t.Fatalf("git %v failed: %v\n%s", args, err, string(out))
		}
		return string(out)
	}

	run("init")
	run("config", "user.name", "Original User")
	run("config", "user.email", "original@example.com")

	if err := os.WriteFile(filepath.Join(repo, "a.txt"), []byte("one\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	run("add", "a.txt")
	run("commit", "-m", "first")

	if err := os.WriteFile(filepath.Join(repo, "a.txt"), []byte("two\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	run("add", "a.txt")
	run("commit", "-m", "second")

	app := NewApp()
	if _, err := app.SetRepository(repo); err != nil {
		t.Fatal(err)
	}

	history, err := app.LoadHistory()
	if err != nil {
		t.Fatal(err)
	}
	if len(history) < 2 {
		t.Fatalf("expected at least 2 commits, got %d", len(history))
	}

	first := history[0]
	first.AuthorName = "Edited Author"
	first.Message = "edited first message"

	req := ApplyRequest{
		Commits:   history,
		ForcePush: false,
		PushTags:  false,
	}
	req.Commits[0] = first

	result, err := app.ApplyChanges(req)
	if err != nil {
		t.Fatal(err)
	}
	if result.RewrittenCommits == 0 {
		t.Fatalf("expected rewritten commits > 0, got %d", result.RewrittenCommits)
	}

	out := run("log", "--reverse", "--pretty=format:%an%x1f%B%x1e")
	if !strings.Contains(out, "Edited Author") {
		t.Fatalf("expected rewritten author in log, got: %s", out)
	}
	if !strings.Contains(out, "edited first message") {
		t.Fatalf("expected rewritten message in log, got: %s", out)
	}
}

func TestRewriteHistoryFailsWhenNoRefsAreRewritten(t *testing.T) {
	repo := t.TempDir()

	run := func(args ...string) string {
		t.Helper()
		cmd := exec.Command("git", append([]string{"-C", repo}, args...)...)
		out, err := cmd.CombinedOutput()
		if err != nil {
			t.Fatalf("git %v failed: %v\n%s", args, err, string(out))
		}
		return string(out)
	}

	run("init")
	run("config", "user.name", "Original User")
	run("config", "user.email", "original@example.com")

	if err := os.WriteFile(filepath.Join(repo, "a.txt"), []byte("one\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	run("add", "a.txt")
	run("commit", "-m", "first")

	app := NewApp()
	if _, err := app.SetRepository(repo); err != nil {
		t.Fatal(err)
	}
	history, err := app.LoadHistory()
	if err != nil {
		t.Fatal(err)
	}
	if len(history) != 1 {
		t.Fatalf("expected one commit, got %d", len(history))
	}

	unchanged := history[0]
	err = rewriteHistory(repo, map[string]CommitRecord{
		unchanged.Hash: unchanged,
	}, map[string]bool{})
	if err == nil {
		t.Fatal("expected rewriteHistory to fail when git reports unchanged refs")
	}
	if !strings.Contains(err.Error(), "did not rewrite any refs") {
		t.Fatalf("unexpected error: %v", err)
	}
}

func TestApplyChangesUpdatesDatesAndRemovesCoAuthorTrailers(t *testing.T) {
	repo := t.TempDir()
	run := func(args ...string) string {
		t.Helper()
		cmd := exec.Command("git", append([]string{"-C", repo}, args...)...)
		out, err := cmd.CombinedOutput()
		if err != nil {
			t.Fatalf("git %v failed: %v\n%s", args, err, string(out))
		}
		return string(out)
	}

	run("init")
	run("config", "user.name", "Original User")
	run("config", "user.email", "original@example.com")
	if err := os.WriteFile(filepath.Join(repo, "a.txt"), []byte("one\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	run("add", "a.txt")
	run("commit", "-m", "subject", "-m", "Context: Co-authored-by: stays because it is prose.\n\nCo-authored-by: One <one@example.com>\nco-authored by: Two <two@example.com>")

	app := NewApp()
	if _, err := app.SetRepository(repo); err != nil {
		t.Fatal(err)
	}
	history, err := app.LoadHistory()
	if err != nil {
		t.Fatal(err)
	}
	history[0].AuthorDate = "2020-06-15 09:30:45 +0530"
	history[0].CommitterDate = "Mon, 15 Jun 2020 04:00:45 +0000"

	result, err := app.ApplyChanges(ApplyRequest{Commits: history, RemoveCoAuthors: true})
	if err != nil {
		t.Fatal(err)
	}
	if result.RemovedCoAuthors != 2 {
		t.Fatalf("expected two removed co-author lines, got %d", result.RemovedCoAuthors)
	}

	log := run("log", "-1", "--pretty=format:%aI%x1f%cI%x1f%B")
	fields := strings.SplitN(log, "\x1f", 3)
	if len(fields) != 3 || !gitDatesEqual(fields[0], "2020-06-15T09:30:45+05:30") || !gitDatesEqual(fields[1], "2020-06-15T04:00:45Z") {
		t.Fatalf("expected exact rewritten dates, got: %s", log)
	}
	if strings.Contains(strings.ToLower(log), "co-authored-by: one") || strings.Contains(strings.ToLower(log), "co-authored by: two") {
		t.Fatalf("expected trailer lines to be removed, got: %s", log)
	}
	if !strings.Contains(log, "Context: Co-authored-by: stays because it is prose.") {
		t.Fatalf("expected non-trailer prose to remain, got: %s", log)
	}
}

func TestRemoveCoAuthorLinesDropsAIAttributionBlocks(t *testing.T) {
	message := "subject\n\nClaude-Session: https://example.com/a\nbody\n\nCo-authored-by: Ada <ada@example.com>\nSigned-off-by: Bob <bob@example.com>\n\nCo-Authored-By: Claude Opus 5 <noreply@anthropic.com>\nClaude-Session: https://example.com/b\nSomething else\n\nCo-authored-by: Codex <codex@openai.com>\nGenerated by Codex\n\ntail"
	cleaned, removed := removeCoAuthorLines(message)
	if removed != 7 {
		t.Fatalf("expected seven removed lines, got %d", removed)
	}
	if cleaned != "subject\n\nbody\n\nSigned-off-by: Bob <bob@example.com>\n\ntail" {
		t.Fatalf("unexpected cleaned message: %q", cleaned)
	}
}

func TestRemoveCoAuthorLinesOnlyMatchesWholeTrailerLines(t *testing.T) {
	message := "subject\r\n\r\nCo-authored-by: Ada <ada@example.com>\r\n  CO-AUTHORED BY: Grace <grace@example.com>\r\nNote: Co-authored-by: this is prose"
	cleaned, removed := removeCoAuthorLines(message)
	if removed != 2 {
		t.Fatalf("expected two removed lines, got %d", removed)
	}
	if strings.Contains(cleaned, "Ada") || strings.Contains(cleaned, "Grace") {
		t.Fatalf("expected co-author trailers to be removed: %q", cleaned)
	}
	if !strings.Contains(cleaned, "Note: Co-authored-by: this is prose") {
		t.Fatalf("expected ordinary prose to remain: %q", cleaned)
	}
}