// Command words holds what the catalogue's modules say to an agent to the glossary's words (novox/hq ADR
// 0244): no word the glossary retired for the tools' descriptions — the copy in retired-words at the
// catalogue's root — in any text a module's tools can show. That text is every string literal in a module's
// own code that is not a test (a tool's description, the notes and errors it answers with) and every
// description in its manifest. Comments are not read: an agent never sees them.
//
// A word is matched whole and in any case, a space in it matching any run of white space, and its plural
// (`s` or `es` on its last part) is matched as the word. A vendor word is
// never on the list (the glossary does not retire one for the tools), so a wrapped program's own objects —
// an identity provider's users, a media manager's releases — are never findings.
//
//	go run . <catalogue root>
//
// Exits 1 on a finding, 2 when the list cannot be read.
package main

import (
	"bufio"
	"encoding/json"
	"fmt"
	"go/scanner"
	"go/token"
	"io/fs"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
)

// text is one piece of text an agent can be shown, and where it starts.
type text struct {
	file string
	line int
	s    string
}

func main() {
	root := "."
	if len(os.Args) > 1 {
		root = os.Args[1]
	}
	words, err := readList(filepath.Join(root, "retired-words"))
	if err != nil {
		fmt.Fprintln(os.Stderr, "words:", err)
		os.Exit(2)
	}
	if len(words) == 0 {
		fmt.Fprintln(os.Stderr, "words: retired-words lists no word — the check would pass on anything")
		os.Exit(2)
	}
	var texts []text
	files := 0
	err = filepath.WalkDir(filepath.Join(root, "modules"), func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() {
			switch d.Name() {
			case "node_modules", "dist", "vendor", "test", "tests", "testdata", ".git":
				return filepath.SkipDir
			}
			return nil
		}
		rel, _ := filepath.Rel(root, path)
		name := d.Name()
		var found []text
		switch {
		case strings.HasSuffix(name, "_test.go"), strings.Contains(name, ".test."), strings.Contains(name, ".spec."):
			return nil
		case strings.HasSuffix(name, ".go"):
			found, err = goStrings(path, rel)
		case strings.HasSuffix(name, ".ts"), strings.HasSuffix(name, ".js"), strings.HasSuffix(name, ".mjs"):
			found, err = scriptStrings(path, rel)
		case name == "module.json":
			found, err = jsonStrings(path, rel)
		default:
			return nil
		}
		if err != nil {
			return fmt.Errorf("%s: %w", rel, err)
		}
		files++
		texts = append(texts, found...)
		return nil
	})
	if err != nil {
		fmt.Fprintln(os.Stderr, "words:", err)
		os.Exit(2)
	}
	findings := check(words, texts)
	for _, f := range findings {
		fmt.Println(f)
	}
	if len(findings) > 0 {
		fmt.Printf("words: %d use(s) of a word the glossary retired (novox/hq ADR 0244) — say it in the glossary's word\n", len(findings))
		os.Exit(1)
	}
	fmt.Printf("words: %d retired words, none in the %d strings of %d files\n", len(words), len(texts), files)
}

// readList reads retired-words: one word or phrase a line; blank lines and lines starting with # are not words.
func readList(path string) ([]string, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer f.Close()
	var words []string
	sc := bufio.NewScanner(f)
	for sc.Scan() {
		line := strings.TrimSpace(sc.Text())
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		words = append(words, line)
	}
	return words, sc.Err()
}

func pattern(word string) *regexp.Regexp {
	parts := strings.Fields(word)
	for i, p := range parts {
		parts[i] = regexp.QuoteMeta(p)
	}
	// The plural is the word too: `s` or `es` on its last part, so "control planes" is found as "control
	// plane" is. Anything else joined on is another word.
	return regexp.MustCompile(`(?i)(?:^|[^\w-])(` + strings.Join(parts, `\s+`) + `(?:e?s)?)(?:$|[^\w-])`)
}

func check(words []string, texts []text) []string {
	var out []string
	for _, w := range words {
		rx := pattern(w)
		for _, t := range texts {
			if m := rx.FindStringSubmatchIndex(t.s); m != nil {
				line := t.line
				if line > 0 {
					line += strings.Count(t.s[:m[2]], "\n")
				}
				out = append(out, fmt.Sprintf("%s:%d: %q is retired — in %q", t.file, line, w, excerpt(t.s, m[2], m[3])))
			}
		}
	}
	sort.Strings(out)
	return out
}

func excerpt(s string, from, to int) string {
	a, b := from-50, to+50
	if a < 0 {
		a = 0
	}
	if b > len(s) {
		b = len(s)
	}
	return strings.Join(strings.Fields(s[a:b]), " ")
}

// goStrings returns a Go file's string literals, adjacent ones joined across `+` as the program joins them.
func goStrings(path, rel string) ([]text, error) {
	src, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	fset := token.NewFileSet()
	file := fset.AddFile(rel, -1, len(src))
	var s scanner.Scanner
	var bad error
	s.Init(file, src, func(pos token.Position, msg string) { bad = fmt.Errorf("%s: %s", pos, msg) }, 0)
	var out []text
	var cur *text
	joining := false
	for {
		pos, tok, lit := s.Scan()
		if tok == token.EOF {
			break
		}
		switch {
		case tok == token.STRING:
			v, err := strconv.Unquote(lit)
			if err != nil {
				v = lit
			}
			if cur != nil && joining {
				cur.s += v
			} else {
				out = append(out, text{file: rel, line: fset.Position(pos).Line, s: v})
				cur = &out[len(out)-1]
			}
			joining = false
		case tok == token.ADD && cur != nil:
			joining = true
		default:
			cur, joining = nil, false
		}
	}
	return out, bad
}

// scriptStrings returns a TypeScript or JavaScript file's string literals, comments skipped, adjacent ones
// joined across `+`. A template literal's `${…}` parts are left out of the text around them.
func scriptStrings(path, rel string) ([]text, error) {
	b, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	src := string(b)
	var out []text
	line := 1
	lastWasString, joining := false, false
	for i := 0; i < len(src); i++ {
		c := src[i]
		switch {
		case c == '\n':
			line++
		case c == '/' && i+1 < len(src) && src[i+1] == '/':
			for i < len(src) && src[i] != '\n' {
				i++
			}
			line++
		case c == '/' && i+1 < len(src) && src[i+1] == '*':
			end := strings.Index(src[i+2:], "*/")
			if end < 0 {
				end = len(src) - i - 2
			}
			line += strings.Count(src[i:i+2+end], "\n")
			i += end + 3
		case c == '"' || c == '\'' || c == '`':
			start := line
			var sb strings.Builder
			depth := 0
			j := i + 1
			for ; j < len(src); j++ {
				d := src[j]
				if d == '\n' {
					line++
				}
				if depth > 0 {
					if d == '\n' {
						sb.WriteByte('\n')
					}
					if d == '{' {
						depth++
					} else if d == '}' {
						depth--
					}
					continue
				}
				if d == '\\' && j+1 < len(src) {
					j++
					sb.WriteByte(src[j])
					continue
				}
				if c == '`' && d == '$' && j+1 < len(src) && src[j+1] == '{' {
					depth = 1
					j++
					sb.WriteByte(' ')
					continue
				}
				if d == c || (c != '`' && d == '\n') {
					break
				}
				sb.WriteByte(d)
			}
			if lastWasString && joining && len(out) > 0 {
				out[len(out)-1].s += sb.String()
			} else {
				out = append(out, text{file: rel, line: start, s: sb.String()})
			}
			lastWasString, joining = true, false
			i = j
			continue
		case c == '+' && lastWasString:
			joining = true
			continue
		case c == ' ' || c == '\t' || c == '\r':
			continue
		default:
			lastWasString, joining = false, false
		}
		if c == '\n' {
			continue
		}
	}
	return out, nil
}

// jsonStrings returns the descriptions in a manifest — every string under a key named "description", at any
// depth. The rest of a manifest is names, paths and the contents of files it places, none of which a tool
// shows an agent.
func jsonStrings(path, rel string) ([]text, error) {
	b, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	var v any
	if err := json.Unmarshal(b, &v); err != nil {
		return nil, err
	}
	var out []text
	var walk func(any, bool)
	walk = func(v any, described bool) {
		switch x := v.(type) {
		case string:
			if described {
				out = append(out, text{file: rel, line: lineOf(string(b), x), s: x})
			}
		case []any:
			for _, e := range x {
				walk(e, described)
			}
		case map[string]any:
			for k, e := range x {
				walk(e, k == "description")
			}
		}
	}
	walk(v, false)
	return out, nil
}

func lineOf(src, s string) int {
	q, _ := json.Marshal(s)
	if i := strings.Index(src, string(q)); i >= 0 {
		return strings.Count(src[:i], "\n") + 1
	}
	return 0
}