package inventory

import (
	"go/ast"
	"go/parser"
	"go/token"
	"io/fs"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"testing"
)

// The tables of the chain, and the column, that the controller's store no longer holds (novox/hq ADR 0408 §8, issue 1096).
var chainTables = []string{"build", "build_request", "release_plan", "batched_merge", "assignment", "pending_assignment"}

// sqlStatement is what makes a literal a statement of the store: it opens with a verb of SQL.
var sqlStatement = regexp.MustCompile(`(?is)^\s*(select|insert|update|delete|alter|drop|create|with|truncate|from|join|where|and|set|values)\b|\b(select\s.+\sfrom|insert\s+into|delete\s+from)\b`)

// **No code names a table of the chain** (acceptance 12, issue 1096), found by reading the sources: a string literal of any
// non-test file of internal/ or cmd/ that names one after from, into, update, join, delete from, references or table —
// build_gate and port_assignment are other words — or the column sent_builds. This is the static half of the proof; the
// integration test reads the catalog.
func TestNoCodeNamesATableOfTheChain(t *testing.T) {
	names := regexp.MustCompile(`(?i)\b(from|into|update|join|delete\s+from|references|table)\s+(` + strings.Join(chainTables, "|") + `)\b|\bsent_builds\b`)
	var found []string
	for _, root := range []string{"../../internal", "../../cmd"} {
		err := filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
			if err != nil {
				return err
			}
			if d.IsDir() && d.Name() == "vendor" {
				return filepath.SkipDir
			}
			if d.IsDir() || !strings.HasSuffix(path, ".go") || strings.HasSuffix(path, "_test.go") {
				return nil
			}
			file, err := parser.ParseFile(token.NewFileSet(), path, nil, 0)
			if err != nil {
				return err
			}
			ast.Inspect(file, func(n ast.Node) bool {
				lit, ok := n.(*ast.BasicLit)
				if !ok || lit.Kind != token.STRING {
					return true
				}
				text, err := strconv.Unquote(lit.Value)
				if err != nil {
					return true
				}
				if !sqlStatement.MatchString(text) {
					return true // prose that happens to say "from assignment" is no statement
				}
				if m := names.FindString(text); m != "" {
					found = append(found, filepath.ToSlash(path)+": "+strings.Join(strings.Fields(m), " "))
				}
				return true
			})
			return nil
		})
		if err != nil {
			t.Fatal(err)
		}
	}
	if len(found) > 0 {
		t.Fatalf("code still names a table of the chain, which the store no longer holds:\n  %s", strings.Join(found, "\n  "))
	}
}

// The scan sees what it says it sees: planted, a string naming a table is found, and a comment or a word beside is not.
func TestTheSourceScanFindsATablePlanted(t *testing.T) {
	names := regexp.MustCompile(`(?i)\b(from|into|update|join|delete\s+from|references|table)\s+(` + strings.Join(chainTables, "|") + `)\b|\bsent_builds\b`)
	for text, want := range map[string]bool{
		"select id from build where id = $1":         true,
		"insert into assignment (node, module)":      true,
		"update node set sent_builds = $1":           true,
		"select 1 from build_gate":                   false,
		"delete from port_assignment":                false,
		"select a from build_request a join build b": true,
		"an assignment from build to build":          true,
		"the assignment generation":                  false,
		"select count(*) from pending_assignment":    true,
	} {
		if got := names.MatchString(text); got != want {
			t.Errorf("%q: %v, want %v", text, got, want)
		}
	}
}

// **The last migration drops the tables of the chain, behind its guard** (issue 1096): it names each table, the column and
// the function, drops no build_gate, and raises before it drops anything.
func TestTheLastMigrationDropsTheTablesOfTheChain(t *testing.T) {
	migrations, err := Migrations()
	if err != nil {
		t.Fatal(err)
	}
	last := migrations[len(migrations)-1]
	if last.Number < 105 {
		t.Fatalf("the last migration is %d", last.Number)
	}
	raw, err := os.ReadFile(filepath.Join("migrations", migrationFile(t, last.Number)))
	if err != nil {
		t.Fatal(err)
	}
	var code []string
	for _, line := range strings.Split(string(raw), "\n") {
		if !strings.HasPrefix(strings.TrimSpace(line), "--") {
			code = append(code, line)
		}
	}
	sql := strings.ToLower(strings.Join(code, "\n"))
	for _, table := range append(append([]string{}, chainTables...), "chain_moved") {
		if !strings.Contains(sql, "drop table "+table+";") {
			t.Errorf("migration %d does not drop %s", last.Number, table)
		}
	}
	for _, want := range []string{"drop function raise_assignment_generation()", "alter table node drop column sent_builds"} {
		if !strings.Contains(sql, want) {
			t.Errorf("migration %d lacks %q", last.Number, want)
		}
	}
	if strings.Contains(sql, "build_gate") || strings.Contains(sql, "assignment_generation;") {
		t.Errorf("migration %d touches a table that stays", last.Number)
	}
	if raise, drop := strings.Index(sql, "raise exception"), strings.Index(sql, "drop table"); raise < 0 || drop < 0 || raise > drop {
		t.Errorf("migration %d does not raise before it drops (%d, %d)", last.Number, raise, drop)
	}
	for _, kind := range []string{"'builds'", "'rollouts'", "'assignments'", "pending_assignment", "chain_moved"} {
		if !strings.Contains(sql[:strings.Index(sql, "drop table")], kind) {
			t.Errorf("the guard of migration %d does not look at %s", last.Number, kind)
		}
	}
}

func migrationFile(t *testing.T, number int) string {
	t.Helper()
	files, err := filepath.Glob(filepath.Join("migrations", strconv.Itoa(number/1000%10)+strconv.Itoa(number/100%10)+strconv.Itoa(number/10%10)+strconv.Itoa(number%10)+"-*.sql"))
	if err != nil || len(files) != 1 {
		t.Fatalf("the file of migration %d: %v %v", number, files, err)
	}
	return filepath.Base(files[0])
}