package core_test

import (
	"bytes"
	"compress/gzip"
	"context"
	"encoding/json"
	"encoding/xml"
	"fmt"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"testing"

	aptclone "github.com/syonad/clonepack/internal/clone/apt"
	rpmclone "github.com/syonad/clonepack/internal/clone/rpm"
	"github.com/syonad/clonepack/internal/store"
)

// --- helpers ---

// buildRPMRepo creates an RPM repo (repomd.xml + upstream primary.xml.gz +
// .primary-source marker) in localDir and writes fake package files on disk.
func buildRPMRepo(t *testing.T, localDir string, pkgs []struct{ name, version, href string }) {
	t.Helper()
	if err := rpmclone.InitEmptyRepo(localDir); err != nil {
		t.Fatalf("InitEmptyRepo: %v", err)
	}

	// Build upstream primary.xml.gz.
	var xmlBuf bytes.Buffer
	xmlBuf.WriteString(`<?xml version="1.0" encoding="UTF-8"?>`)
	fmt.Fprintf(&xmlBuf, `<metadata xmlns="http://linux.duke.edu/metadata/common" packages="%d">`, len(pkgs))
	for _, p := range pkgs {
		fmt.Fprintf(&xmlBuf,
			`<package type="rpm"><name>%s</name>`+
				`<version epoch="0" ver="%s" rel="1"/>`+
				`<arch>x86_64</arch>`+
				`<checksum type="sha256" pkgid="YES">abc%s</checksum>`+
				`<size package="1024" installed="2048" archive="1500"/>`+
				`<location href="%s"/>`+
				`</package>`,
			p.name, p.version, p.name, p.href)
	}
	xmlBuf.WriteString(`</metadata>`)

	var gz bytes.Buffer
	gzw := gzip.NewWriter(&gz)
	gzw.Write(xmlBuf.Bytes())
	gzw.Close()

	upstreamPath := filepath.Join(localDir, "repodata", "upstream-primary.xml.gz")
	if err := os.WriteFile(upstreamPath, gz.Bytes(), 0o644); err != nil {
		t.Fatalf("write upstream primary: %v", err)
	}

	// .primary-source marker so RegenerateMetadata always filters from upstream.
	marker := filepath.Join(localDir, "repodata", rpmclone.PrimarySourceFile)
	if err := os.WriteFile(marker, []byte("repodata/upstream-primary.xml.gz"), 0o644); err != nil {
		t.Fatalf("write .primary-source: %v", err)
	}

	// Minimal repomd.xml pointing at the upstream (regen will redirect to local).
	type loc struct {
		Href string `xml:"href,attr"`
	}
	type chk struct {
		Type  string `xml:"type,attr"`
		Value string `xml:",chardata"`
	}
	type entry struct {
		Type     string `xml:"type,attr"`
		Location loc    `xml:"location"`
		Checksum chk    `xml:"checksum"`
	}
	type repomdDoc struct {
		XMLName xml.Name `xml:"repomd"`
		Data    []entry  `xml:"data"`
	}
	rm := repomdDoc{Data: []entry{{
		Type:     "primary",
		Location: loc{Href: "repodata/upstream-primary.xml.gz"},
		Checksum: chk{Type: "sha256", Value: "placeholder"},
	}}}
	repomdXML, _ := xml.MarshalIndent(rm, "", "  ")
	if err := os.WriteFile(
		filepath.Join(localDir, "repodata", "repomd.xml"),
		append([]byte(xml.Header), repomdXML...),
		0o644,
	); err != nil {
		t.Fatalf("write repomd.xml: %v", err)
	}

	// Create fake package files.
	for _, p := range pkgs {
		dest := filepath.Join(localDir, filepath.FromSlash(p.href))
		os.MkdirAll(filepath.Dir(dest), 0o755)
		os.WriteFile(dest, []byte("fake-rpm"), 0o644)
	}

	// Regenerate so repomd.xml reflects actual checksums.
	if err := rpmclone.RegenerateMetadata(localDir); err != nil {
		t.Fatalf("RegenerateMetadata: %v", err)
	}
}

// buildAPTRepo creates an APT repo with Packages files and fake deb files on disk.
func buildAPTRepo(t *testing.T, localDir string, cfg aptclone.Config, debs []struct{ pkg, version, filename string }) {
	t.Helper()
	if err := aptclone.InitEmptyRepo(localDir, cfg); err != nil {
		t.Fatalf("InitEmptyRepo apt: %v", err)
	}

	var stanzas []string
	for _, d := range debs {
		stanzas = append(stanzas, strings.Join([]string{
			"Package: " + d.pkg,
			"Version: " + d.version,
			"Architecture: amd64",
			"Filename: " + d.filename,
			"SHA256: abc" + d.pkg,
			"Size: 1024",
		}, "\n"))
	}

	plain := []byte(strings.Join(stanzas, "\n\n") + "\n")
	var gz bytes.Buffer
	gzw := gzip.NewWriter(&gz)
	gzw.Write(plain)
	gzw.Close()
	gzData := gz.Bytes()

	for _, component := range cfg.Components {
		for _, arch := range cfg.Architectures {
			binDir := filepath.Join(localDir, "dists", cfg.Suite, component, "binary-"+arch)
			os.MkdirAll(binDir, 0o755)
			os.WriteFile(filepath.Join(binDir, ".upstream-Packages.gz"), gzData, 0o644)
		}
	}

	for _, d := range debs {
		dest := filepath.Join(localDir, filepath.FromSlash(d.filename))
		os.MkdirAll(filepath.Dir(dest), 0o755)
		os.WriteFile(dest, []byte("fake-deb"), 0o644)
	}

	if err := aptclone.RegenerateMetadata(localDir, cfg); err != nil {
		t.Fatalf("RegenerateMetadata apt: %v", err)
	}
}

// --- TakeSnapshot RPM ---

func TestTakeSnapshot_RPM_capturesPackages(t *testing.T) {
	env := newTestEnv(t)
	ctx := context.Background()

	repoID, _ := env.repoStore.CreateRepo(ctx, &store.Repo{
		Name: "rpm-repo", Type: "rpm", SourceURL: "https://example.com", SyncMode: "manual",
	})
	localDir := filepath.Join(env.dataDir, "repos", "1", "rpm")
	buildRPMRepo(t, localDir, []struct{ name, version, href string }{
		{"curl", "7.88", "Packages/curl-7.88-1.x86_64.rpm"},
		{"wget", "1.21", "Packages/wget-1.21-1.x86_64.rpm"},
	})

	snapID, err := env.snapshotSvc.TakeSnapshot(ctx, repoID, "v1")
	if err != nil {
		t.Fatalf("TakeSnapshot: %v", err)
	}

	pkgs, _ := env.snapshotStore.GetSnapshotPackages(ctx, snapID)
	if len(pkgs) != 2 {
		t.Fatalf("expected 2 packages, got %d", len(pkgs))
	}
	names := map[string]bool{}
	for _, p := range pkgs {
		names[p.Name] = true
	}
	if !names["curl"] || !names["wget"] {
		t.Errorf("unexpected package names: %v", names)
	}
}

func TestTakeSnapshot_RPM_emptyRepo(t *testing.T) {
	env := newTestEnv(t)
	ctx := context.Background()

	repoID, _ := env.repoStore.CreateRepo(ctx, &store.Repo{
		Name: "rpm-empty", Type: "rpm", SourceURL: "https://example.com", SyncMode: "manual",
	})
	localDir := filepath.Join(env.dataDir, "repos", "1", "rpm")
	buildRPMRepo(t, localDir, nil)

	snapID, err := env.snapshotSvc.TakeSnapshot(ctx, repoID, "empty")
	if err != nil {
		t.Fatalf("TakeSnapshot: %v", err)
	}
	pkgs, _ := env.snapshotStore.GetSnapshotPackages(ctx, snapID)
	if len(pkgs) != 0 {
		t.Errorf("expected 0 packages, got %d", len(pkgs))
	}
}

func TestTakeSnapshot_repoNotFound(t *testing.T) {
	env := newTestEnv(t)
	_, err := env.snapshotSvc.TakeSnapshot(context.Background(), 9999, "v1")
	if err == nil {
		t.Error("expected error for unknown repo")
	}
}

// --- TakeSnapshot APT ---

func TestTakeSnapshot_APT_capturesPackages(t *testing.T) {
	env := newTestEnv(t)
	ctx := context.Background()

	cfg := aptclone.Config{Suite: "bookworm", Components: []string{"main"}, Architectures: []string{"amd64"}}
	cfgJSON, _ := json.Marshal(cfg)
	repoID, _ := env.repoStore.CreateRepo(ctx, &store.Repo{
		Name: "apt-repo", Type: "apt", SourceURL: "https://deb.debian.org/debian",
		SyncMode: "manual", Config: string(cfgJSON),
	})
	localDir := filepath.Join(env.dataDir, "repos", "1", "apt")
	buildAPTRepo(t, localDir, cfg, []struct{ pkg, version, filename string }{
		{"curl", "7.88.1-10", "pool/main/c/curl/curl_7.88.1-10_amd64.deb"},
		{"vim", "2:9.0.1378-2", "pool/main/v/vim/vim_9.0.1378-2_amd64.deb"},
	})

	snapID, err := env.snapshotSvc.TakeSnapshot(ctx, repoID, "apt-v1")
	if err != nil {
		t.Fatalf("TakeSnapshot APT: %v", err)
	}
	pkgs, _ := env.snapshotStore.GetSnapshotPackages(ctx, snapID)
	if len(pkgs) != 2 {
		t.Fatalf("expected 2 packages, got %d", len(pkgs))
	}
}

func TestTakeSnapshot_APT_deduplicatesAcrossComponents(t *testing.T) {
	env := newTestEnv(t)
	ctx := context.Background()

	cfg := aptclone.Config{
		Suite: "bookworm", Components: []string{"main", "contrib"}, Architectures: []string{"amd64"},
	}
	cfgJSON, _ := json.Marshal(cfg)
	repoID, _ := env.repoStore.CreateRepo(ctx, &store.Repo{
		Name: "apt-multi", Type: "apt", SourceURL: "https://deb.debian.org/debian",
		SyncMode: "manual", Config: string(cfgJSON),
	})
	localDir := filepath.Join(env.dataDir, "repos", "1", "apt")
	aptclone.InitEmptyRepo(localDir, cfg)

	// Same .deb appears in both components.
	stanza := strings.Join([]string{
		"Package: shared-pkg",
		"Version: 1.0",
		"Architecture: amd64",
		"Filename: pool/main/s/shared-pkg/shared-pkg_1.0_amd64.deb",
		"SHA256: abcdef",
		"Size: 1024",
	}, "\n") + "\n"

	var gz bytes.Buffer
	gzw := gzip.NewWriter(&gz)
	gzw.Write([]byte(stanza))
	gzw.Close()
	gzData := gz.Bytes()

	for _, component := range cfg.Components {
		binDir := filepath.Join(localDir, "dists", cfg.Suite, component, "binary-amd64")
		os.MkdirAll(binDir, 0o755)
		os.WriteFile(filepath.Join(binDir, ".upstream-Packages.gz"), gzData, 0o644)
	}
	dest := filepath.Join(localDir, "pool/main/s/shared-pkg/shared-pkg_1.0_amd64.deb")
	os.MkdirAll(filepath.Dir(dest), 0o755)
	os.WriteFile(dest, []byte("fake-deb"), 0o644)
	aptclone.RegenerateMetadata(localDir, cfg)

	snapID, err := env.snapshotSvc.TakeSnapshot(ctx, repoID, "dedup-test")
	if err != nil {
		t.Fatalf("TakeSnapshot: %v", err)
	}
	pkgs, _ := env.snapshotStore.GetSnapshotPackages(ctx, snapID)
	if len(pkgs) != 1 {
		t.Errorf("expected 1 deduplicated package, got %d", len(pkgs))
	}
}

// --- Diff ---

func TestDiff_addsAndRemoves(t *testing.T) {
	env := newTestEnv(t)
	ctx := context.Background()

	repoID, _ := env.repoStore.CreateRepo(ctx, &store.Repo{
		Name: "rpm-repo", Type: "rpm", SourceURL: "https://example.com", SyncMode: "manual",
	})

	snap1ID, _ := env.snapshotStore.CreateSnapshot(ctx, repoID, "v1")
	env.snapshotStore.AddSnapshotPackages(ctx, snap1ID, []store.SnapshotPackage{
		{Name: "curl", Version: "7.88-1", Arch: "x86_64", Location: "Packages/curl.rpm", ChecksumType: "sha256"},
		{Name: "wget", Version: "1.21-1", Arch: "x86_64", Location: "Packages/wget.rpm", ChecksumType: "sha256"},
	})

	snap2ID, _ := env.snapshotStore.CreateSnapshot(ctx, repoID, "v2")
	env.snapshotStore.AddSnapshotPackages(ctx, snap2ID, []store.SnapshotPackage{
		{Name: "curl", Version: "7.88-1", Arch: "x86_64", Location: "Packages/curl.rpm", ChecksumType: "sha256"},
		{Name: "vim", Version: "9.0-1", Arch: "x86_64", Location: "Packages/vim.rpm", ChecksumType: "sha256"},
	})

	diff, err := env.snapshotSvc.Diff(ctx, repoID, snap1ID, snap2ID)
	if err != nil {
		t.Fatalf("Diff: %v", err)
	}
	if diff.Unchanged != 1 {
		t.Errorf("Unchanged: got %d, want 1", diff.Unchanged)
	}
	if len(diff.Added) != 1 || diff.Added[0].Name != "vim" {
		t.Errorf("Added: got %v, want [vim]", diff.Added)
	}
	if len(diff.Removed) != 1 || diff.Removed[0].Name != "wget" {
		t.Errorf("Removed: got %v, want [wget]", diff.Removed)
	}
}

func TestDiff_wrongRepo(t *testing.T) {
	env := newTestEnv(t)
	ctx := context.Background()

	id1, _ := env.repoStore.CreateRepo(ctx, &store.Repo{Name: "r1", Type: "rpm", SourceURL: "https://a.com", SyncMode: "manual"})
	id2, _ := env.repoStore.CreateRepo(ctx, &store.Repo{Name: "r2", Type: "rpm", SourceURL: "https://b.com", SyncMode: "manual"})

	snap1ID, _ := env.snapshotStore.CreateSnapshot(ctx, id1, "s1")
	snap2ID, _ := env.snapshotStore.CreateSnapshot(ctx, id2, "s2")

	_, err := env.snapshotSvc.Diff(ctx, id1, snap1ID, snap2ID)
	if err == nil {
		t.Error("expected error when snapshots belong to different repos")
	}
}

// --- Rollback ---

func TestRollback_removesExtraFiles(t *testing.T) {
	env := newTestEnv(t)
	ctx := context.Background()

	repoID, _ := env.repoStore.CreateRepo(ctx, &store.Repo{
		Name: "rpm-repo", Type: "rpm", SourceURL: "https://example.com", SyncMode: "manual",
	})
	localDir := filepath.Join(env.dataDir, "repos", "1", "rpm")
	buildRPMRepo(t, localDir, []struct{ name, version, href string }{
		{"curl", "7.88", "Packages/curl-7.88-1.x86_64.rpm"},
		{"wget", "1.21", "Packages/wget-1.21-1.x86_64.rpm"},
	})

	// Snapshot records only curl.
	snapID, _ := env.snapshotStore.CreateSnapshot(ctx, repoID, "curl-only")
	env.snapshotStore.AddSnapshotPackages(ctx, snapID, []store.SnapshotPackage{
		{Name: "curl", Version: "7.88-1", Arch: "x86_64",
			Location: "Packages/curl-7.88-1.x86_64.rpm", ChecksumType: "sha256"},
	})

	curlPath := filepath.Join(localDir, "Packages", "curl-7.88-1.x86_64.rpm")
	wgetPath := filepath.Join(localDir, "Packages", "wget-1.21-1.x86_64.rpm")

	if err := env.snapshotSvc.Rollback(ctx, repoID, snapID); err != nil {
		t.Fatalf("Rollback: %v", err)
	}

	if _, err := os.Stat(wgetPath); err == nil {
		t.Error("wget should have been removed by rollback")
	}
	if _, err := os.Stat(curlPath); err != nil {
		t.Errorf("curl should still be present: %v", err)
	}
}

func TestRollback_redownloadsMissingFiles(t *testing.T) {
	const fileContent = "fake-rpm-bytes"
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte(fileContent))
	}))
	defer srv.Close()

	env := newTestEnv(t)
	ctx := context.Background()

	repoID, _ := env.repoStore.CreateRepo(ctx, &store.Repo{
		Name: "rpm-repo", Type: "rpm", SourceURL: srv.URL, SyncMode: "manual",
	})
	localDir := filepath.Join(env.dataDir, "repos", "1", "rpm")
	buildRPMRepo(t, localDir, []struct{ name, version, href string }{
		{"curl", "7.88", "Packages/curl-7.88-1.x86_64.rpm"},
	})

	snapID, _ := env.snapshotStore.CreateSnapshot(ctx, repoID, "v1")
	env.snapshotStore.AddSnapshotPackages(ctx, snapID, []store.SnapshotPackage{
		{Name: "curl", Version: "7.88-1", Arch: "x86_64",
			Location: "Packages/curl-7.88-1.x86_64.rpm", ChecksumType: "sha256"},
	})

	curlPath := filepath.Join(localDir, "Packages", "curl-7.88-1.x86_64.rpm")
	os.Remove(curlPath)

	if err := env.snapshotSvc.Rollback(ctx, repoID, snapID); err != nil {
		t.Fatalf("Rollback: %v", err)
	}
	if _, err := os.Stat(curlPath); err != nil {
		t.Errorf("curl should have been re-downloaded: %v", err)
	}
}