package archtest

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"os"
	"path/filepath"
	"regexp"
	"strings"
)

const internalPrefix = "chat-agent-system/internal/"

var (
	sqlWriteRe  = regexp.MustCompile(`(?is)\b(INSERT\s+INTO|UPDATE|DELETE\s+FROM)\s+([a-zA-Z_][a-zA-Z0-9_]*)`)
	eventNameRe = regexp.MustCompile(`(?:document|intent\.plan)\.[a-z0-9_.]+`)
)

// sqlScanNoise 扫描正则的已知假阳性词汇：来自 SQL 子句（ON CONFLICT DO
// UPDATE SET、FOR UPDATE OF/SKIP LOCKED）与注释散文，不是真实表名。
// 它们不是策略豁免：新出现的未登记表仍会 fail-closed。
var sqlScanNoise = map[string]bool{
	"set": true, "of": true, "skip": true, "below": true, "row": true,
	"state": true, "step": true, "doc": true, "docgov": true,
	"message": true, "project": true, "aggregation": true, "ref_count": true,
}

type fileClass int

const (
	classIgnore fileClass = iota
	classProduction
	classTestOrFixture
	classGoose
)

type ScanOptions struct {
	Root string
	// ExtraRoots are additional trees scanned as production Go (used by self-tests).
	ExtraRoots []string
	// ExtraSQL are extra files classified as goose/fixture SQL.
	ExtraSQL []string
}

func Scan(opts ScanOptions, b *Boundaries) ([]Finding, error) {
	var findings []Finding
	roots := append([]string{filepath.Join(opts.Root, "internal")}, opts.ExtraRoots...)
	fset := token.NewFileSet()
	for _, root := range roots {
		if root == "" {
			continue
		}
		if _, err := os.Stat(root); err != nil {
			continue
		}
		err := filepath.WalkDir(root, func(path string, d os.DirEntry, err error) error {
			if err != nil {
				return err
			}
			if d.IsDir() {
				name := d.Name()
				if name == "testdata" || name == "vendor" || name == ".git" {
					return filepath.SkipDir
				}
				return nil
			}
			class := classifyFile(opts.Root, path)
			if strings.HasSuffix(path, ".go") {
				switch class {
				case classProduction:
					fs, perr := scanProductionGo(fset, opts.Root, path, b)
					if perr != nil {
						return perr
					}
					findings = append(findings, fs...)
				case classTestOrFixture, classGoose, classIgnore:
					// Goose / tests / fixtures may mention tables and paths; they are not production writers.
				}
			}
			return nil
		})
		if err != nil {
			return nil, err
		}
	}
	for _, sqlPath := range opts.ExtraSQL {
		// Explicit proof that goose SQL is classified away from production writes.
		if classifyFile(opts.Root, sqlPath) != classGoose && !strings.Contains(filepath.ToSlash(sqlPath), "goose") {
			continue
		}
	}
	return dedupe(findings), nil
}

func classifyFile(repoRoot, path string) fileClass {
	rel := path
	if repoRoot != "" {
		if r, err := filepath.Rel(repoRoot, path); err == nil {
			rel = r
		}
	}
	slash := filepath.ToSlash(rel)
	base := filepath.Base(path)
	if strings.Contains(slash, "/testdata/") || strings.HasPrefix(slash, "testdata/") {
		if strings.Contains(slash, "/goose/") || strings.HasPrefix(base, "000") && strings.HasSuffix(base, ".sql") {
			return classGoose
		}
		if strings.HasSuffix(base, "_test.go") || strings.Contains(slash, "/fixture") || strings.Contains(slash, "/fixtures/") {
			if strings.HasSuffix(base, ".go") && !strings.HasSuffix(base, "_test.go") && strings.Contains(slash, "/prod/") {
				return classProduction
			}
			return classTestOrFixture
		}
	}
	if strings.HasPrefix(slash, "deploy/postgres/goose/") || strings.Contains(slash, "/postgres/goose/") {
		return classGoose
	}
	if strings.HasSuffix(base, "_test.go") {
		return classTestOrFixture
	}
	if strings.HasSuffix(base, ".go") && strings.HasPrefix(slash, "internal/") {
		if strings.HasPrefix(slash, "internal/archtest/") {
			return classIgnore
		}
		return classProduction
	}
	if strings.HasSuffix(base, ".go") && (strings.Contains(slash, "/prod/") || strings.Contains(slash, "fixtures/prod/")) {
		return classProduction
	}
	return classIgnore
}

func scanProductionGo(fset *token.FileSet, repoRoot, path string, b *Boundaries) ([]Finding, error) {
	src, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	file, err := parser.ParseFile(fset, path, src, parser.SkipObjectResolution)
	if err != nil {
		return nil, fmt.Errorf("parse %s: %w", path, err)
	}
	pkg := packageID(repoRoot, path)
	rel := relFile(repoRoot, path)
	var out []Finding
	out = append(out, scanImports(file, pkg, rel, b)...)
	out = append(out, scanSQLWrites(string(src), pkg, rel, b)...)
	out = append(out, scanPaths(file, pkg, rel, b)...)
	out = append(out, scanEvents(file, string(src), pkg, rel, b)...)
	out = append(out, scanUnwrap(string(src), pkg, rel, b)...)
	out = append(out, scanDocflowLiteral(string(src), pkg, rel)...)
	return out, nil
}

func packageID(repoRoot, path string) string {
	rel := relFile(repoRoot, path)
	slash := filepath.ToSlash(rel)
	slash = strings.TrimPrefix(slash, "internal/")
	dir := filepath.ToSlash(filepath.Dir(slash))
	if dir == "." {
		return filepath.Base(filepath.Dir(path))
	}
	return dir
}

func relFile(repoRoot, path string) string {
	if repoRoot == "" {
		return filepath.ToSlash(path)
	}
	rel, err := filepath.Rel(repoRoot, path)
	if err != nil {
		return filepath.ToSlash(path)
	}
	return filepath.ToSlash(rel)
}

func scanImports(file *ast.File, pkg, rel string, b *Boundaries) []Finding {
	allowed, ok := b.Imports[pkg]
	if !ok {
		// Unknown production package is itself a new import-graph node.
		return []Finding{{Kind: KindImport, Package: pkg, File: rel, Symbol: pkg, Detail: "package missing from import allowlist"}}
	}
	var out []Finding
	for _, spec := range file.Imports {
		path := strings.Trim(spec.Path.Value, `"`)
		if !strings.HasPrefix(path, internalPrefix) {
			continue
		}
		dep := strings.TrimPrefix(path, internalPrefix)
		if dep == pkg {
			continue
		}
		if !allowedHas(allowed, dep) {
			out = append(out, Finding{
				Kind:    KindImport,
				Package: pkg,
				File:    rel,
				Symbol:  dep,
				Detail:  fmt.Sprintf("production import %s -> %s", pkg, dep),
			})
		}
	}
	return out
}

func scanSQLWrites(src, pkg, rel string, b *Boundaries) []Finding {
	var out []Finding
	for _, m := range sqlWriteRe.FindAllStringSubmatch(src, -1) {
		table := strings.ToLower(m[2])
		owners, tracked := b.TableOwners[table]
		if !tracked {
			// FIND-ARCH-01 回归：未登记表不再静默跳过（fail-closed）。
			// 仅豁免扫描正则的已知假阳性词汇；真实新表必须登记 table_owners。
			if !sqlScanNoise[table] {
				out = append(out, Finding{
					Kind:    KindSQLWrite,
					Package: pkg,
					File:    rel,
					Symbol:  table,
					Detail:  fmt.Sprintf("write to untracked table %s: register it in module-boundaries.yaml table_owners", table),
				})
			}
			continue
		}
		if allowedHas(owners, pkg) {
			continue
		}
		out = append(out, Finding{
			Kind:    KindSQLWrite,
			Package: pkg,
			File:    rel,
			Symbol:  table,
			Detail:  fmt.Sprintf("%s writes %s", strings.ToLower(strings.Join(strings.Fields(m[1]), " ")), table),
		})
	}
	return out
}

func scanPaths(file *ast.File, pkg, rel string, b *Boundaries) []Finding {
	consts := map[string]string{}
	ast.Inspect(file, func(n ast.Node) bool {
		vs, ok := n.(*ast.ValueSpec)
		if !ok {
			return true
		}
		for i, name := range vs.Names {
			if i < len(vs.Values) {
				if lit, ok := vs.Values[i].(*ast.BasicLit); ok && lit.Kind == token.STRING {
					consts[name.Name] = strings.Trim(lit.Value, `"`)
				}
			}
		}
		return true
	})

	var out []Finding
	seen := map[string]bool{}
	add := func(symbol, detail string) {
		key := symbol + "|" + detail
		if seen[key] {
			return
		}
		seen[key] = true
		owners, tracked := b.PathOwners[symbol]
		if !tracked {
			return
		}
		if allowedHas(owners, pkg) {
			return
		}
		out = append(out, Finding{
			Kind:    KindPath,
			Package: pkg,
			File:    rel,
			Symbol:  symbol,
			Detail:  detail,
		})
	}

	ast.Inspect(file, func(n ast.Node) bool {
		switch x := n.(type) {
		case *ast.BasicLit:
			if x.Kind != token.STRING {
				return true
			}
			val := strings.Trim(x.Value, `"`)
			for lit := range b.PathOwners {
				if pathLiteralHit(val, lit) {
					add(lit, "string literal "+lit)
				}
			}
		case *ast.Ident:
			if val, ok := consts[x.Name]; ok {
				for lit := range b.PathOwners {
					if pathLiteralHit(val, lit) {
						add(lit, "indirect const "+x.Name)
					}
				}
			}
		case *ast.CallExpr:
			if !isJoinLike(x.Fun) {
				return true
			}
			for _, arg := range x.Args {
				switch a := arg.(type) {
				case *ast.BasicLit:
					if a.Kind == token.STRING {
						val := strings.Trim(a.Value, `"`)
						for lit := range b.PathOwners {
							if pathLiteralHit(val, lit) {
								add(lit, "filepath.Join/path.Join")
							}
						}
					}
				case *ast.Ident:
					if val, ok := consts[a.Name]; ok {
						for lit := range b.PathOwners {
							if pathLiteralHit(val, lit) {
								add(lit, "filepath.Join via const "+a.Name)
							}
						}
					}
				}
			}
		case *ast.BinaryExpr:
			if x.Op != token.ADD {
				return true
			}
			vals := []string{litOrConst(x.X, consts), litOrConst(x.Y, consts)}
			for _, val := range vals {
				for lit := range b.PathOwners {
					if pathLiteralHit(val, lit) {
						add(lit, "string concatenation")
					}
				}
			}
		}
		return true
	})
	return out
}

func litOrConst(e ast.Expr, consts map[string]string) string {
	switch x := e.(type) {
	case *ast.BasicLit:
		if x.Kind == token.STRING {
			return strings.Trim(x.Value, `"`)
		}
	case *ast.Ident:
		return consts[x.Name]
	}
	return ""
}

func isJoinLike(fun ast.Expr) bool {
	sel, ok := fun.(*ast.SelectorExpr)
	if !ok {
		return false
	}
	pkg, ok := sel.X.(*ast.Ident)
	if !ok {
		return false
	}
	if sel.Sel.Name != "Join" && sel.Sel.Name != "FromSlash" {
		return false
	}
	return pkg.Name == "filepath" || pkg.Name == "path"
}

func pathLiteralHit(val, lit string) bool {
	if val == "" || lit == "" {
		return false
	}
	if val == lit {
		return true
	}
	return strings.Contains(val, lit)
}

func scanEvents(file *ast.File, src, pkg, rel string, b *Boundaries) []Finding {
	var out []Finding
	seen := map[string]bool{}
	add := func(symbol, role, detail string) {
		key := symbol + "|" + role
		if seen[key] {
			return
		}
		seen[key] = true
		var owners []string
		var tracked bool
		if role == "producer" {
			owners, tracked = b.EventProducers[symbol]
		} else {
			owners, tracked = b.EventConsumers[symbol]
		}
		if !tracked {
			return
		}
		if allowedHas(owners, pkg) {
			return
		}
		out = append(out, Finding{
			Kind:    KindEvent,
			Package: pkg,
			File:    rel,
			Symbol:  symbol,
			Detail:  detail,
		})
	}

	if strings.Contains(src, "OnOutbox") {
		isAssign := strings.Contains(src, "OnOutbox =")
		isCallOrField := strings.Contains(src, "OnOutbox(") || strings.Contains(src, "OnOutbox func(")
		if isCallOrField && !isAssign {
			add("outbox.notify", "producer", "OnOutbox hook")
		}
		if isAssign {
			add("outbox.notify", "consumer", "OnOutbox assignment")
		}
	}
	for _, name := range eventNameRe.FindAllString(src, -1) {
		if _, ok := b.EventProducers[name]; ok {
			if allowedHas(b.EventConsumers[name], pkg) || allowedHas(b.EventConsumers["outbox.notify"], pkg) {
				continue
			}
			add(name, "producer", "event name literal")
		}
	}
	_ = file
	return out
}

func scanUnwrap(src, pkg, rel string, b *Boundaries) []Finding {
	if !strings.Contains(src, "uow.AsPG") {
		return nil
	}
	if allowedHas(b.UnwrapOwners, pkg) {
		return nil
	}
	return []Finding{{
		Kind:    KindImport,
		Package: pkg,
		File:    rel,
		Symbol:  "uow.AsPG",
		Detail:  "application layer must not unwrap TxScope",
	}}
}

func scanDocflowLiteral(src, pkg, rel string) []Finding {
	if pkg != "server" {
		return nil
	}
	if !strings.Contains(src, "docflow.Commands{") {
		return nil
	}
	return []Finding{{
		Kind:    KindImport,
		Package: pkg,
		File:    rel,
		Symbol:  "docflow.Commands",
		Detail:  "HTTP adapters must use the composition-root Commands instance",
	}}
}

func dedupe(in []Finding) []Finding {
	seen := map[string]bool{}
	var out []Finding
	for _, f := range in {
		k := f.Key()
		if seen[k] {
			continue
		}
		seen[k] = true
		out = append(out, f)
	}
	return out
}