package pipeline

import (
	"bytes"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/buildinfo"
	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/erf"
	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/project"
)

const directProjectConfig = `{
  "module": {
    "name": "Test Module",
    "resref": "testmod",
    "hak_order": ["core_01"]
  },
  "paths": {
    "source": "src",
    "assets": "assets",
    "build": "build"
  }
}
`

func writeBlobAt(t *testing.T, root, sha, content string) {
	t.Helper()
	dir := filepath.Join(root, "sha256", sha[0:2], sha[2:4])
	mustMkdir(t, dir)
	mustWriteFile(t, filepath.Join(dir, sha), content)
}

func writeBlob(t *testing.T, root string, payload []byte) string {
	t.Helper()
	sum := sha256.Sum256(payload)
	sha := hex.EncodeToString(sum[:])
	writeBlobAt(t, root, sha, string(payload))
	return sha
}

func writeDirectManifest(t *testing.T, root string, sources map[string]SourceAsset, assets []string) string {
	t.Helper()
	manifest := SourceBuildManifest{
		Schema:     1,
		BuilderID:  buildinfo.String(),
		ModuleHAKs: []string{"core_01"},
		HAKs: []SourceManifestHAK{{
			Name:     "core_01",
			Group:    "core",
			Priority: 1,
			MaxBytes: 1 << 20,
			Assets:   assets,
		}},
		AssetSources: sources,
	}
	raw, err := json.Marshal(manifest)
	if err != nil {
		t.Fatalf("marshal manifest: %v", err)
	}
	path := filepath.Join(root, "build-source-manifest.json")
	mustWriteFile(t, path, string(raw))
	return path
}

func loadDirectProject(t *testing.T, root string) *project.Project {
	t.Helper()
	mustWriteFile(t, filepath.Join(root, "nwn-tool.json"), directProjectConfig)
	mustMkdir(t, filepath.Join(root, "build"))
	p, err := project.Load(root)
	if err != nil {
		t.Fatalf("load project: %v", err)
	}
	return p
}

func TestBuildHAKsFromContentAddressedManifestWithoutAssetsTree(t *testing.T) {
	root := t.TempDir()
	p := loadDirectProject(t, root)

	blobs := filepath.Join(root, "blobs")
	payload := []byte("tga-payload-bytes")
	sha := writeBlob(t, blobs, payload)
	manifestPath := writeDirectManifest(t, root,
		map[string]SourceAsset{"core/a.tga": {SHA256: sha, SizeBytes: int64(len(payload))}},
		[]string{"core/a.tga"})

	result, err := BuildHAKsWithOptions(p, BuildHAKOptions{
		SourceManifestPath:   manifestPath,
		ContentAddressedRoot: blobs,
	})
	if err != nil {
		t.Fatalf("build direct haks: %v", err)
	}
	if result.HAKAssets != 1 {
		t.Fatalf("hak assets = %d, want 1", result.HAKAssets)
	}

	if _, err := os.Stat(filepath.Join(root, "assets")); !errors.Is(err, os.ErrNotExist) {
		t.Fatalf("direct build must not materialize an assets tree (stat err = %v)", err)
	}

	hakPath := filepath.Join(root, "build", "core_01.hak")
	raw, err := os.ReadFile(hakPath)
	if err != nil {
		t.Fatalf("read hak: %v", err)
	}
	archive, err := erf.Read(bytes.NewReader(raw))
	if err != nil {
		t.Fatalf("decode hak: %v", err)
	}
	if len(archive.Resources) != 1 {
		t.Fatalf("hak resources = %d, want 1", len(archive.Resources))
	}
	if got := string(archive.Resources[0].Data); got != string(payload) {
		t.Fatalf("resource payload = %q, want %q", got, payload)
	}
	if archive.Resources[0].Name != "a" {
		t.Fatalf("resref = %q, want a", archive.Resources[0].Name)
	}
}

func TestBuildHAKsFromContentAddressedManifestRejectsMissingRoot(t *testing.T) {
	root := t.TempDir()
	p := loadDirectProject(t, root)

	blobs := filepath.Join(root, "blobs")
	payload := []byte("tga-payload-bytes")
	sha := writeBlob(t, blobs, payload)
	manifestPath := writeDirectManifest(t, root,
		map[string]SourceAsset{"core/a.tga": {SHA256: sha, SizeBytes: int64(len(payload))}},
		[]string{"core/a.tga"})

	_, err := BuildHAKsWithOptions(p, BuildHAKOptions{SourceManifestPath: manifestPath})
	if err == nil {
		t.Fatal("expected failure when content-addressed root is missing")
	}
}

func TestBuildHAKsFromContentAddressedManifestRejectsMissingBlob(t *testing.T) {
	root := t.TempDir()
	p := loadDirectProject(t, root)

	blobs := filepath.Join(root, "blobs")
	sha := strings.Repeat("b", 64)
	manifestPath := writeDirectManifest(t, root,
		map[string]SourceAsset{"core/a.tga": {SHA256: sha, SizeBytes: 4}},
		[]string{"core/a.tga"})

	_, err := BuildHAKsWithOptions(p, BuildHAKOptions{
		SourceManifestPath:   manifestPath,
		ContentAddressedRoot: blobs,
	})
	if err == nil {
		t.Fatal("expected failure for missing source blob")
	}
}

func TestBuildHAKsFromContentAddressedManifestRejectsCorruptBlob(t *testing.T) {
	root := t.TempDir()
	p := loadDirectProject(t, root)

	blobs := filepath.Join(root, "blobs")
	declared := sha256.Sum256([]byte("abcd"))
	sha := hex.EncodeToString(declared[:])
	// Same length, different bytes: size check passes, content hash mismatches.
	writeBlobAt(t, blobs, sha, "wxyz")
	manifestPath := writeDirectManifest(t, root,
		map[string]SourceAsset{"core/a.tga": {SHA256: sha, SizeBytes: 4}},
		[]string{"core/a.tga"})

	_, err := BuildHAKsWithOptions(p, BuildHAKOptions{
		SourceManifestPath:   manifestPath,
		ContentAddressedRoot: blobs,
	})
	if err == nil {
		t.Fatal("expected sha256 mismatch failure for corrupt blob")
	}
	if !strings.Contains(err.Error(), "sha256 mismatch") {
		t.Fatalf("error = %v, want sha256 mismatch", err)
	}
	if _, statErr := os.Stat(filepath.Join(root, "build", "core_01.hak")); !errors.Is(statErr, os.ErrNotExist) {
		t.Fatalf("corrupt build must not leave a completed hak (stat err = %v)", statErr)
	}
}

func TestLegacySourceManifestStillBuildsFromAssetsTree(t *testing.T) {
	root := t.TempDir()
	mustMkdir(t, filepath.Join(root, "src", "module"))
	mustMkdir(t, filepath.Join(root, "assets", "core"))
	mustMkdir(t, filepath.Join(root, "build"))
	mustWriteFile(t, filepath.Join(root, "nwn-tool.json"), `{
  "module": {"name": "Test Module", "resref": "testmod", "hak_order": ["group:core"]},
  "paths": {"source": "src", "assets": "assets", "build": "build"},
  "haks": [{"name": "core", "priority": 1, "include": ["core/**"]}]
}
`)
	mustWriteFile(t, filepath.Join(root, "src", "module", "module.ifo.json"), `{
  "file_type": "IFO ",
  "file_version": "V3.2",
  "root": {"struct_type": 0, "fields": [
    {"label": "Mod_Name", "type": "CExoString", "value": "Test Module"},
    {"label": "Mod_HakList", "type": "List", "value": []}
  ]}
}
`)
	mustWriteFile(t, filepath.Join(root, "assets", "core", "a.tga"), strings.Repeat("a", 16))
	mustWriteFile(t, filepath.Join(root, "assets", "core", "b.tga"), strings.Repeat("b", 16))

	manifestPath := filepath.Join(root, "legacy-source-manifest.json")
	mustWriteFile(t, manifestPath, `{
  "module_haks": ["core"],
  "haks": [{"name": "core", "group": "core", "priority": 1, "assets": ["core/a.tga", "core/b.tga"]}]
}
`)

	p, err := project.Load(root)
	if err != nil {
		t.Fatalf("load project: %v", err)
	}
	if err := p.Scan(); err != nil {
		t.Fatalf("scan: %v", err)
	}

	result, err := BuildHAKsWithOptions(p, BuildHAKOptions{SourceManifestPath: manifestPath})
	if err != nil {
		t.Fatalf("legacy build: %v", err)
	}
	if len(result.HAKPaths) != 1 {
		t.Fatalf("hak paths = %d, want 1", len(result.HAKPaths))
	}
	raw, err := os.ReadFile(filepath.Join(root, "build", "core.hak"))
	if err != nil {
		t.Fatalf("read legacy hak: %v", err)
	}
	archive, err := erf.Read(bytes.NewReader(raw))
	if err != nil {
		t.Fatalf("decode legacy hak: %v", err)
	}
	if len(archive.Resources) != 2 {
		t.Fatalf("legacy hak resources = %d, want 2", len(archive.Resources))
	}
}