package infra

import (
	"database/sql"
	"os"
	"path/filepath"
	"testing"

	_ "github.com/mattn/go-sqlite3"
)

// createTestRegistryDB creates a minimal registry.db with the given apps and
// a single function (random_hex_id_go_core in domain core, lang go).
func createTestRegistryDB(t *testing.T, root string, apps []struct {
	id            string
	lang          string
	dirPath       string
	usesFunctions string
}) {
	t.Helper()
	dbPath := filepath.Join(root, "registry.db")
	db, err := sql.Open("sqlite3", dbPath)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Close()

	_, err = db.Exec(`
CREATE TABLE functions (
	id TEXT PRIMARY KEY,
	name TEXT,
	domain TEXT,
	lang TEXT,
	signature TEXT,
	file_path TEXT
);
CREATE TABLE apps (
	id TEXT PRIMARY KEY,
	lang TEXT,
	dir_path TEXT,
	uses_functions TEXT DEFAULT '[]'
);
INSERT INTO functions (id, name, domain, lang, file_path)
	VALUES ('random_hex_id_go_core','random_hex_id','core','go','functions/core/random_hex_id.go');
`)
	if err != nil {
		t.Fatal(err)
	}
	for _, a := range apps {
		_, err = db.Exec(
			`INSERT INTO apps (id, lang, dir_path, uses_functions) VALUES (?,?,?,?)`,
			a.id, a.lang, a.dirPath, a.usesFunctions,
		)
		if err != nil {
			t.Fatalf("insert app %s: %v", a.id, err)
		}
	}
}

// TestAuditUsesFunctions_DetectsMissing verifies that a Go app that calls
// RandomHexID in its source but declares empty uses_functions gets
// random_hex_id_go_core reported as missing.
func TestAuditUsesFunctions_DetectsMissing(t *testing.T) {
	t.Run("missing function detected for Go app", func(t *testing.T) {
		root := t.TempDir()
		createTestRegistryDB(t, root, []struct {
			id, lang, dirPath, usesFunctions string
		}{
			{"testapp_go_tools", "go", "apps/testapp", `[]`},
		})

		appDir := filepath.Join(root, "apps", "testapp")
		if err := os.MkdirAll(appDir, 0755); err != nil {
			t.Fatal(err)
		}
		goSrc := `package main

import (
	"fmt"
	"fn-registry/functions/core"
)

func main() {
	id := core.RandomHexID(8)
	fmt.Println(id)
}
`
		if err := os.WriteFile(filepath.Join(appDir, "main.go"), []byte(goSrc), 0644); err != nil {
			t.Fatal(err)
		}

		results, err := AuditUsesFunctions(root)
		if err != nil {
			t.Fatalf("AuditUsesFunctions: %v", err)
		}
		if len(results) != 1 {
			t.Fatalf("expected 1 result, got %d", len(results))
		}
		got := results[0]
		if len(got.Missing) != 1 || got.Missing[0] != "random_hex_id_go_core" {
			t.Errorf("Missing = %v, want [random_hex_id_go_core]", got.Missing)
		}
		if len(got.Unused) != 0 {
			t.Errorf("Unused = %v, want []", got.Unused)
		}
	})
}

// TestAuditUsesFunctions_DetectsUnused verifies that a function declared in
// uses_functions but not called in source is reported as unused.
func TestAuditUsesFunctions_DetectsUnused(t *testing.T) {
	t.Run("unused function detected for Go app", func(t *testing.T) {
		root := t.TempDir()
		createTestRegistryDB(t, root, []struct {
			id, lang, dirPath, usesFunctions string
		}{
			{"testapp2_go_tools", "go", "apps/testapp2", `["random_hex_id_go_core"]`},
		})

		appDir := filepath.Join(root, "apps", "testapp2")
		if err := os.MkdirAll(appDir, 0755); err != nil {
			t.Fatal(err)
		}
		goSrc := `package main

import "fmt"

func main() { fmt.Println("hello") }
`
		if err := os.WriteFile(filepath.Join(appDir, "main.go"), []byte(goSrc), 0644); err != nil {
			t.Fatal(err)
		}

		results, err := AuditUsesFunctions(root)
		if err != nil {
			t.Fatalf("AuditUsesFunctions: %v", err)
		}
		if len(results) != 1 {
			t.Fatalf("expected 1 result, got %d", len(results))
		}
		got := results[0]
		if len(got.Unused) != 1 || got.Unused[0] != "random_hex_id_go_core" {
			t.Errorf("Unused = %v, want [random_hex_id_go_core]", got.Unused)
		}
		if len(got.Missing) != 0 {
			t.Errorf("Missing = %v, want []", got.Missing)
		}
	})
}

// TestSnakeToPascal_HandlesAbbreviations verifies the commonAbbrevs expansion
// (issue 0057, Fase 1). Each "want" is the exported Go symbol the registry
// actually uses for that snake_case name. It also pins the deliberate
// non-mappings (cdp, pdf): the registry's own convention is mixed-case there,
// so the abbreviation must NOT fire.
func TestSnakeToPascal_HandlesAbbreviations(t *testing.T) {
	cases := []struct{ in, want string }{
		// New abbreviations added by issue 0057 (verified against real func names).
		{"fetch_ohlcv", "FetchOHLCV"},
		{"normalize_ohlcv", "NormalizeOHLCV"},
		{"duckdb_open", "DuckDBOpen"},
		{"load_ohlcv_from_duckdb", "LoadOHLCVFromDuckDB"},
		{"clickhouse_open", "ClickHouseOpen"},
		{"nordvpn_container_run", "NordVPNContainerRun"},
		{"parse_nordvpn_status", "ParseNordVPNStatus"},
		{"hash_sha256", "HashSHA256"},
		{"hash_md5", "HashMD5"},
		{"strip_ansi", "StripANSI"},
		{"parse_ip_cidr", "ParseIPCIDR"},
		{"open_aead", "OpenAEAD"},
		{"seal_aead", "SealAEAD"},
		{"pty_capture_stream", "PTYCaptureStream"},
		{"setup_vps_app", "SetupVPSApp"},
		{"vps_setup_app", "VPSSetupApp"},
		{"wg_keygen", "WGKeygen"},
		{"wg_peer_add", "WGPeerAdd"},
		{"vt_render", "VTRender"},
		{"fft", "FFT"},
		{"ema", "EMA"},
		{"rsi", "RSI"},
		{"sma", "SMA"},
		{"vwap", "VWAP"},
		{"cdp_get_ax_outline", "CdpGetAXOutline"},
		{"audit_e2e_coverage", "AuditE2ECoverage"},
		{"e2e_run_checks", "E2ERunChecks"},
		{"extract_urls", "ExtractURLs"},
		// Pre-existing abbreviations (regression guard — must keep working).
		{"http_json_response", "HTTPJSONResponse"},
		{"sqlite_open", "SQLiteOpen"},
		{"random_hex_id", "RandomHexID"},
		// Deliberate non-mappings: registry uses mixed-case (Cdp, Pdf) here, so
		// the snake_case→Pascal conversion must leave them mixed-case. These are
		// the cases the .go fallback (Fase 2) and the signature path cover.
		{"cdp_get_html", "CdpGetHTML"},
		{"cdp_navigate", "CdpNavigate"},
		{"pdf_simple_report", "PdfSimpleReport"},
	}
	for _, c := range cases {
		if got := snakeToPascal(c.in); got != c.want {
			t.Errorf("snakeToPascal(%q) = %q, want %q", c.in, got, c.want)
		}
	}
}

// goFallbackEnv builds a minimal registry.db + app on disk for the .go fallback
// test. The registry function gen_wails_crud_go_infra mimics wails_bind_crud:
// its signature omits the `func` keyword (so the signature regex misses) and its
// PascalCase("gen_wails_crud")="GenWailsCRUD" differs from the real exported
// symbol "GenerateWailsCRUD". The app calls the real symbol. When writeFnFile is
// true, the registry .go file exists and the fallback can recover the symbol.
func goFallbackEnv(t *testing.T, fnFilePath string, writeFnFile bool) UsesFunctionsAudit {
	t.Helper()
	root := t.TempDir()
	dbPath := filepath.Join(root, "registry.db")
	db, err := sql.Open("sqlite3", dbPath)
	if err != nil {
		t.Fatal(err)
	}
	_, err = db.Exec(`
CREATE TABLE functions (id TEXT PRIMARY KEY, name TEXT, domain TEXT, lang TEXT, signature TEXT, file_path TEXT);
CREATE TABLE apps (id TEXT PRIMARY KEY, lang TEXT, dir_path TEXT, uses_functions TEXT DEFAULT '[]');
`)
	if err != nil {
		t.Fatal(err)
	}
	_, err = db.Exec(
		`INSERT INTO functions (id,name,domain,lang,signature,file_path) VALUES (?,?,?,?,?,?)`,
		"gen_wails_crud_go_infra", "gen_wails_crud", "infra", "go",
		"GenerateWailsCRUD(spec WailsCRUDSpec) string", fnFilePath,
	)
	if err != nil {
		t.Fatal(err)
	}
	_, err = db.Exec(
		`INSERT INTO apps (id,lang,dir_path,uses_functions) VALUES (?,?,?,?)`,
		"myapp_go_infra", "go", "apps/myapp", `["gen_wails_crud_go_infra"]`,
	)
	if err != nil {
		t.Fatal(err)
	}
	db.Close()

	if writeFnFile {
		fnAbsDir := filepath.Join(root, filepath.Dir(fnFilePath))
		if err := os.MkdirAll(fnAbsDir, 0755); err != nil {
			t.Fatal(err)
		}
		src := "package infra\n\ntype WailsCRUDSpec struct{}\n\nfunc GenerateWailsCRUD(spec WailsCRUDSpec) string { return \"\" }\n"
		if err := os.WriteFile(filepath.Join(root, fnFilePath), []byte(src), 0644); err != nil {
			t.Fatal(err)
		}
	}

	appDir := filepath.Join(root, "apps", "myapp")
	if err := os.MkdirAll(appDir, 0755); err != nil {
		t.Fatal(err)
	}
	appSrc := "package main\n\nimport (\n\t\"fmt\"\n\t\"fn-registry/functions/infra\"\n)\n\nfunc main() {\n\tfmt.Println(infra.GenerateWailsCRUD(infra.WailsCRUDSpec{}))\n}\n"
	if err := os.WriteFile(filepath.Join(appDir, "main.go"), []byte(appSrc), 0644); err != nil {
		t.Fatal(err)
	}

	results, err := AuditUsesFunctions(root)
	if err != nil {
		t.Fatalf("AuditUsesFunctions: %v", err)
	}
	if len(results) != 1 {
		t.Fatalf("expected 1 result, got %d", len(results))
	}
	return results[0]
}

// TestAuditUsesFunctions_GoFileFallback verifies the .go fallback (issue 0057,
// Fase 2): when neither the registry signature nor PascalCase(name) yields the
// real exported symbol, the auditor reads the function's .go file to recover it,
// so a genuinely-used function is not a false "unused". The error sub-case (file
// absent) shows the fallback degrades gracefully and the function is then
// correctly reported unused — proving the fallback is load-bearing.
func TestAuditUsesFunctions_GoFileFallback(t *testing.T) {
	t.Run("golden: .go fallback recovers real symbol -> not unused", func(t *testing.T) {
		got := goFallbackEnv(t, "functions/infra/gen_wails_crud.go", true)
		if len(got.Unused) != 0 {
			t.Errorf("Unused = %v, want [] (fallback should find GenerateWailsCRUD)", got.Unused)
		}
		if len(got.Missing) != 0 {
			t.Errorf("Missing = %v, want []", got.Missing)
		}
	})

	t.Run("error: missing .go file -> flagged unused, no crash", func(t *testing.T) {
		got := goFallbackEnv(t, "functions/infra/gen_wails_crud.go", false)
		if len(got.Unused) != 1 || got.Unused[0] != "gen_wails_crud_go_infra" {
			t.Errorf("Unused = %v, want [gen_wails_crud_go_infra] (no fallback file to read)", got.Unused)
		}
	})
}

// TestAuditUsesFunctions_SharedGoFileNotMisattributed pins the regression caught
// during issue 0057 verification: several registry functions can share one .go
// file (the "TU adicional" pattern, e.g. cdp_new_tab living in cdp_list_tabs.go).
// Because they have valid signatures, the .go fallback must stay GATED OFF for
// them — otherwise the file's first exported func (here ListTabs) would be
// mis-attributed to a sibling (NewTab) and suppress a genuine "unused" finding.
// The app below uses only ListTabs; NewTab must remain flagged unused.
func TestAuditUsesFunctions_SharedGoFileNotMisattributed(t *testing.T) {
	root := t.TempDir()
	dbPath := filepath.Join(root, "registry.db")
	db, err := sql.Open("sqlite3", dbPath)
	if err != nil {
		t.Fatal(err)
	}
	_, err = db.Exec(`
CREATE TABLE functions (id TEXT PRIMARY KEY, name TEXT, domain TEXT, lang TEXT, signature TEXT, file_path TEXT);
CREATE TABLE apps (id TEXT PRIMARY KEY, lang TEXT, dir_path TEXT, uses_functions TEXT DEFAULT '[]');
INSERT INTO functions (id,name,domain,lang,signature,file_path) VALUES
	('list_tabs_go_browser','list_tabs','browser','go','func ListTabs() error','functions/browser/tabs.go'),
	('new_tab_go_browser','new_tab','browser','go','func NewTab() error','functions/browser/tabs.go');
INSERT INTO apps (id,lang,dir_path,uses_functions) VALUES
	('tabsapp_go_browser','go','apps/tabsapp','["list_tabs_go_browser","new_tab_go_browser"]');
`)
	if err != nil {
		t.Fatal(err)
	}
	db.Close()

	// Shared registry .go file: ListTabs is the FIRST exported func.
	fnDir := filepath.Join(root, "functions", "browser")
	if err := os.MkdirAll(fnDir, 0755); err != nil {
		t.Fatal(err)
	}
	tabsSrc := "package browser\n\nfunc ListTabs() error { return nil }\n\nfunc NewTab() error { return nil }\n"
	if err := os.WriteFile(filepath.Join(fnDir, "tabs.go"), []byte(tabsSrc), 0644); err != nil {
		t.Fatal(err)
	}

	// App calls only ListTabs, but declares both.
	appDir := filepath.Join(root, "apps", "tabsapp")
	if err := os.MkdirAll(appDir, 0755); err != nil {
		t.Fatal(err)
	}
	appSrc := "package main\n\nimport (\n\t\"fmt\"\n\t\"fn-registry/functions/browser\"\n)\n\nfunc main() {\n\tfmt.Println(browser.ListTabs())\n}\n"
	if err := os.WriteFile(filepath.Join(appDir, "main.go"), []byte(appSrc), 0644); err != nil {
		t.Fatal(err)
	}

	results, err := AuditUsesFunctions(root)
	if err != nil {
		t.Fatalf("AuditUsesFunctions: %v", err)
	}
	if len(results) != 1 {
		t.Fatalf("expected 1 result, got %d", len(results))
	}
	got := results[0]
	if len(got.Unused) != 1 || got.Unused[0] != "new_tab_go_browser" {
		t.Errorf("Unused = %v, want [new_tab_go_browser] (sibling must NOT rescue via shared file)", got.Unused)
	}
}

// TestGoRealExportedName verifies the .go symbol extractor: top-level exported
// funcs (plain and generic) are recovered, method receivers are skipped, the
// result is cached, and unreadable/empty paths return "" without error.
func TestGoRealExportedName(t *testing.T) {
	root := t.TempDir()
	if err := os.MkdirAll(filepath.Join(root, "functions", "infra"), 0755); err != nil {
		t.Fatal(err)
	}
	// File whose first exported func is preceded by an unexported func + a method.
	src := "package infra\n\n" +
		"import \"fmt\"\n\n" +
		"func helper() {}\n\n" +
		"type T struct{}\n\n" +
		"func (t *T) Save() {}\n\n" +
		"func GenerateWailsCRUD(spec int) string { fmt.Println(spec); return \"\" }\n\n" +
		"func WailsStreamData[X any](xs []X) {}\n"
	rel := "functions/infra/sample.go"
	if err := os.WriteFile(filepath.Join(root, rel), []byte(src), 0644); err != nil {
		t.Fatal(err)
	}
	cache := map[string]string{}

	t.Run("golden: first top-level exported func (skips helper + method)", func(t *testing.T) {
		if got := goRealExportedName(root, rel, cache); got != "GenerateWailsCRUD" {
			t.Errorf("got %q, want GenerateWailsCRUD", got)
		}
		if cache[rel] != "GenerateWailsCRUD" {
			t.Errorf("cache[%q] = %q, want GenerateWailsCRUD", rel, cache[rel])
		}
	})

	t.Run("edge: generic func form func Name[T any](", func(t *testing.T) {
		genRel := "functions/infra/gen.go"
		genSrc := "package infra\n\nfunc WailsStreamData[X any](xs []X) {}\n"
		if err := os.WriteFile(filepath.Join(root, genRel), []byte(genSrc), 0644); err != nil {
			t.Fatal(err)
		}
		if got := goRealExportedName(root, genRel, cache); got != "WailsStreamData" {
			t.Errorf("got %q, want WailsStreamData", got)
		}
	})

	t.Run("error: missing file -> empty string, cached", func(t *testing.T) {
		missRel := "functions/infra/does_not_exist.go"
		if got := goRealExportedName(root, missRel, cache); got != "" {
			t.Errorf("got %q, want empty for missing file", got)
		}
		if v, ok := cache[missRel]; !ok || v != "" {
			t.Errorf("missing file should be cached as empty, got ok=%v v=%q", ok, v)
		}
	})

	t.Run("error: empty file_path -> empty string", func(t *testing.T) {
		if got := goRealExportedName(root, "", cache); got != "" {
			t.Errorf("got %q, want empty for empty path", got)
		}
	})
}

// TestAuditUsesFunctions_MissingDir verifies that apps whose dir_path does not
// exist on disk get an entry with nil Missing/Unused slices (cannot inspect).
func TestAuditUsesFunctions_MissingDir(t *testing.T) {
	t.Run("missing dir returns entry with nil slices", func(t *testing.T) {
		root := t.TempDir()
		createTestRegistryDB(t, root, []struct {
			id, lang, dirPath, usesFunctions string
		}{
			{"testapp3_go_tools", "go", "apps/testapp3", `[]`},
		})
		// intentionally do NOT create apps/testapp3 on disk

		results, err := AuditUsesFunctions(root)
		if err != nil {
			t.Fatalf("AuditUsesFunctions: %v", err)
		}
		if len(results) != 1 {
			t.Fatalf("expected 1 result, got %d", len(results))
		}
		got := results[0]
		if got.Missing != nil {
			t.Errorf("Missing should be nil for missing dir, got %v", got.Missing)
		}
		if got.Unused != nil {
			t.Errorf("Unused should be nil for missing dir, got %v", got.Unused)
		}
	})
}