// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: MIT

package main

import (
	"errors"
	"flag"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"sourcedock.dev/petrbalvin/interpres/v2"
)

const sampleConfig = `listen = ":2049"
log-ops = true
state-dir = "/var/lib/nfsd"
max-connections = 64

[tls]
cert = "/etc/nfsd/cert.pem"
key = "/etc/nfsd/key.pem"

[[export]]
path = "/srv/demo"
read-only = true
`

func writeConfig(t *testing.T, body string) string {
	t.Helper()
	p := filepath.Join(t.TempDir(), "nfsd.toml")
	if err := os.WriteFile(p, []byte(body), 0o600); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}
	return p
}

// TestLoadConfig reads the whole sample back, every table and key.
func TestLoadConfig(t *testing.T) {
	cfg, err := loadConfig(writeConfig(t, sampleConfig))
	if err != nil {
		t.Fatalf("load: %v", err)
	}
	if cfg.Listen != ":2049" || !cfg.LogOps || cfg.StateDir != "/var/lib/nfsd" ||
		cfg.MaxConnections != 64 {
		t.Fatalf("scalars: %+v", cfg)
	}
	if cfg.TLS == nil || cfg.TLS.Cert != "/etc/nfsd/cert.pem" || cfg.TLS.Key != "/etc/nfsd/key.pem" {
		t.Fatalf("tls: %+v", cfg.TLS)
	}
	if len(cfg.Exports) != 1 || cfg.Exports[0].Path != "/srv/demo" || !cfg.Exports[0].ReadOnly {
		t.Fatalf("exports: %+v", cfg.Exports)
	}
}

// TestLoadConfigEmptyPath covers the explicitness rule: no -config, no
// file read, zero configuration.
func TestLoadConfigEmptyPath(t *testing.T) {
	cfg, err := loadConfig("")
	if err != nil {
		t.Fatalf("load: %v", err)
	}
	if cfg.Listen != "" || len(cfg.Exports) != 0 {
		t.Fatalf("an empty path answered %+v", cfg)
	}
}

// TestLoadConfigUnknownKey rejects a key the schema does not carry: a
// typo in the file must end the start up, not slip through.
func TestLoadConfigUnknownKey(t *testing.T) {
	_, err := loadConfig(writeConfig(t, "lisn = \":2049\"\n"))
	if err == nil {
		t.Fatal("an unknown key was accepted")
	}
	var se *interpres.SyntaxError
	if !errors.As(err, &se) && !strings.Contains(err.Error(), "lisn") &&
		!strings.Contains(err.Error(), "unknown") {
		t.Fatalf("the error names neither the key nor its kind: %v", err)
	}
}

// TestLoadConfigSyntaxError reports the file and the line of a broken
// document.
func TestLoadConfigSyntaxError(t *testing.T) {
	p := writeConfig(t, "listen = \":2049\"\nbroken")
	_, err := loadConfig(p)
	if err == nil {
		t.Fatal("a broken document was accepted")
	}
	if !strings.Contains(err.Error(), p+":2:") {
		t.Fatalf("the error misses the file or the line: %v", err)
	}
}

// TestLoadConfigOneExport enforces the exactly one export contract.
func TestLoadConfigOneExport(t *testing.T) {
	if _, err := loadConfig(writeConfig(t, "listen = \":2049\"")); err == nil {
		t.Fatal("a file without an export was accepted")
	}
	if _, err := loadConfig(writeConfig(t,
		"[[export]]\npath = \"/a\"\n\n[[export]]\npath = \"/b\"\n")); err == nil {
		t.Fatal("a file with two exports was accepted")
	}
	if _, err := loadConfig(writeConfig(t, "[[export]]\nread-only = true\n")); err == nil {
		t.Fatal("an export without a path was accepted")
	}
}

// newTestFlags builds the flag set of main with the same names and
// defaults.
func newTestFlags() (addr, export *string, ro, logOps *bool, tlsCert, tlsKey, stateDir *string,
	maxConns *int, fs *flag.FlagSet) {
	fs = flag.NewFlagSet("nfsd-test", flag.ContinueOnError)
	addr = fs.String("addr", ":2049", "")
	export = fs.String("export", "", "")
	ro = fs.Bool("ro", false, "")
	tlsCert = fs.String("tls-cert", "", "")
	tlsKey = fs.String("tls-key", "", "")
	logOps = fs.Bool("log-ops", false, "")
	stateDir = fs.String("state-dir", "", "")
	maxConns = fs.Int("max-connections", 0, "")
	return
}

// TestApplyConfigFillsUnsetFlags: the file is the base.
func TestApplyConfigFillsUnsetFlags(t *testing.T) {
	cfg, err := loadConfig(writeConfig(t, sampleConfig))
	if err != nil {
		t.Fatalf("load: %v", err)
	}
	addr, export, ro, logOps, tlsCert, tlsKey, stateDir, maxConns, fs := newTestFlags()
	applyConfig(cfg, fs, func(string) bool { return false })
	if *addr != ":2049" || *export != "/srv/demo" || !*ro || !*logOps ||
		*stateDir != "/var/lib/nfsd" || *maxConns != 64 ||
		*tlsCert != "/etc/nfsd/cert.pem" || *tlsKey != "/etc/nfsd/key.pem" {
		t.Fatalf("flags after the file: addr=%q export=%q ro=%v logOps=%v stateDir=%q maxConns=%d tls=%q,%q",
			*addr, *export, *ro, *logOps, *stateDir, *maxConns, *tlsCert, *tlsKey)
	}
}

// TestApplyConfigFlagsWin: the flags override the file.
func TestApplyConfigFlagsWin(t *testing.T) {
	cfg, err := loadConfig(writeConfig(t, sampleConfig))
	if err != nil {
		t.Fatalf("load: %v", err)
	}
	addr, export, ro, logOps, tlsCert, tlsKey, stateDir, maxConns, fs := newTestFlags()
	fs.Parse([]string{"-addr", ":9999", "-export", "/other", "-ro=false", "-log-ops=false"})
	given := make(map[string]bool)
	fs.Visit(func(f *flag.Flag) { given[f.Name] = true })
	applyConfig(cfg, fs, func(name string) bool { return given[name] })
	if *addr != ":9999" {
		t.Fatalf("addr %q, the command line must win", *addr)
	}
	if *export != "/other" {
		t.Fatalf("export %q, the command line must win", *export)
	}
	if *ro {
		t.Fatal("ro must stay false, the command line set it")
	}
	if *logOps {
		t.Fatal("log-ops must stay false, the command line set it")
	}
	if *stateDir != "/var/lib/nfsd" || *maxConns != 64 || *tlsCert == "" || *tlsKey == "" {
		t.Fatalf("the file lost the keys the command line left alone: stateDir=%q maxConns=%d tls=%q,%q",
			*stateDir, *maxConns, *tlsCert, *tlsKey)
	}
}