clerk @ 1b9e6e1

package journal

import (

	"bytes"

	"fmt"

	"io/fs"

	"os"

	"path/filepath"

	"slices"

	"strings"

	"sync"

	"olexsmir.xyz/clerk/journal/ast"

	"olexsmir.xyz/clerk/journal/lexer"

	"olexsmir.xyz/clerk/journal/parser"

)

type ParsedFile struct {

	Path       string

	Src        []byte // file content; token literals in Ast alias it, must NOT be mutated after parsing

	Ast        *ast.Journal

	FileErrors []*ast.FileError

	Errors     []*ast.ParseError

}

// ResolvedItem is one item in an occurrence-ordered flat view; child items inlined at include site.

type ResolvedItem struct {

	Occurrence *ParsedFile

	IsInclude  bool // true for IncludeDirective entries (skipped by consumers)

	EntryIndex int  // index into Occurrence.Ast.Entries

}

// ResolvedJournal is a flat, occurrence-ordered view of a journal tree.

// Resolve/ResolveBytes returns a fresh journal; same source path may appear

// as multiple occurrences with different parser contexts.

type ResolvedJournal struct {

	Occurrences []*ParsedFile  // all occurrences in depth-first order

	Items       []ResolvedItem // flat stream, occur-order

	ByPath      map[string][]*ParsedFile

}

// FileErrors returns all file errors from all occurrences.

func (rj *ResolvedJournal) FileErrors() []*ast.FileError {

	var all []*ast.FileError

	for _, pf := range rj.Occurrences {

		all = append(all, pf.FileErrors...)

	}

	return all

}

// parseCacheMax bounds the number of parsed files retained by the loader.

const parseCacheMax = 64

type parseKey struct {

	canon, content string

	defaultYear    int

}

type parseEntry struct {

	src []byte

	ast *ast.Journal

}

// Loader include-aware journal parsing caching.

type Loader struct {

	mu           sync.RWMutex

	contentCache map[string][]byte // canonical path: normalised content

	parseCache   map[parseKey]parseEntry

	// ContentProvider, when set, is consulted before any disk read. It returns

	// the file's authoritative content and ok=true, or ok=false to fall back to

	// disk. The zero value (nil) keeps the loader disk-only.

	ContentProvider func(path string) ([]byte, bool)

}

func NewLoader() *Loader {

	return &Loader{

		contentCache: make(map[string][]byte),

		parseCache:   make(map[parseKey]parseEntry),

	}

}

// Resolve performs a fresh include-aware parse of fpath, returning a flat

// occurrence view. Same file may appear multiple times when included from

// multiple sites.

func (l *Loader) Resolve(fpath string) (*ResolvedJournal, error) {

	src, err := l.readContent(fpath)

	if err != nil {

		return nil, err

	}

	return l.ResolveBytes(fpath, src), nil

}

// ResolveBytes is like [Loader.Resolve] but parses from a byte slice; includes resolved relative to fpath.

func (l *Loader) ResolveBytes(fpath string, src []byte) *ResolvedJournal {

	rj := &ResolvedJournal{

		ByPath: make(map[string][]*ParsedFile),

	}

	l.resolveOccurrence(rj, nil, fpath, src, 0, nil)

	return rj

}

// ResolveFiles resolves multiple entry files into one flat view.

func (l *Loader) ResolveFiles(paths []string) *ResolvedJournal {

	rj := &ResolvedJournal{

		ByPath: make(map[string][]*ParsedFile),

	}

	for _, p := range paths {

		src, err := l.readContent(p)

		if err != nil {

			continue

		}

		l.resolveOccurrence(rj, nil, p, src, 0, nil)

	}

	return rj

}

// ResolveFS loads a journal from [fs.FS] via temp dir.

func (l *Loader) ResolveFS(fsys fs.FS, fpath string) (*ResolvedJournal, error) {

	dir, err := os.MkdirTemp("", "clerk-loadfs-*")

	if err != nil {

		return nil, fmt.Errorf("creating temp dir: %w", err)

	}

	defer os.RemoveAll(dir)

	if cerr := os.CopyFS(dir, fsys); cerr != nil {

		return nil, fmt.Errorf("copying fs to temp dir: %w", cerr)

	}

	rj, err := l.Resolve(filepath.Join(dir, fpath))

	if err != nil {

		return nil, err

	}

	// remap temp dir paths to FS-relative paths for deterministic output

	l.remapFilePaths(rj, dir)

	return rj, nil

}

func (l *Loader) remapFilePaths(rj *ResolvedJournal, oldRoot string) {

	for _, pf := range rj.Occurrences {

		if rel, err := filepath.Rel(oldRoot, pf.Path); err == nil {

			pf.Path = filepath.ToSlash(rel)

		}

	}

	newByPath := make(map[string][]*ParsedFile, len(rj.ByPath))

	for oldPath, pfs := range rj.ByPath {

		rel, err := filepath.Rel(oldRoot, oldPath)

		newPath := oldPath

		if err == nil {

			newPath = filepath.ToSlash(rel)

		}

		newByPath[newPath] = pfs

	}

	rj.ByPath = newByPath

}

// InvalidateFile removes a file from the content cache.

func (l *Loader) InvalidateFile(fpath string) {

	canon := CanonicalPath(fpath)

	l.mu.Lock()

	delete(l.contentCache, canon)

	l.mu.Unlock()

}

// Evict drops a file's cached content.

func (l *Loader) Evict(fpath string) {

	canon := CanonicalPath(fpath)

	l.mu.Lock()

	defer l.mu.Unlock()

	delete(l.contentCache, canon)

	for k := range l.parseCache {

		if k.canon == canon {

			delete(l.parseCache, k)

		}

	}

}

// readContent reads a file, preferring the content provider, then the disk content cache.

func (l *Loader) readContent(fpath string) ([]byte, error) {

	if l.ContentProvider != nil {

		if content, ok := l.ContentProvider(fpath); ok {

			return normaliseNewlines(content), nil

		}

	}

	canon := CanonicalPath(fpath)

	l.mu.RLock()

	content, ok := l.contentCache[canon]

	l.mu.RUnlock()

	if ok {

		return content, nil

	}

	raw, err := os.ReadFile(fpath)

	if err != nil {

		return nil, err

	}

	content = normaliseNewlines(raw)

	l.mu.Lock()

	l.contentCache[canon] = content

	l.mu.Unlock()

	return content, nil

}

func normaliseNewlines(raw []byte) []byte {

	content := bytes.ReplaceAll(raw, []byte("\r\n"), []byte("\n"))

	return bytes.ReplaceAll(content, []byte("\r"), []byte("\n"))

}

// resolveOccurrence recursively parses one occurrence and its includes

func (l *Loader) resolveOccurrence(rj *ResolvedJournal, parent *ParsedFile, fpath string, src []byte, defaultYear int, stack []string) {

	// cycle detection uses canonical paths to catch cycles through symlinks.

	canon := CanonicalPath(fpath)

	if slices.Contains(stack, canon) {

		if parent != nil {

			parent.FileErrors = append(parent.FileErrors, &ast.FileError{

				Path:    fpath,

				Message: fmt.Sprintf("include cycle: %s", strings.Join(append(stack, canon), " → ")),

			})

		}

		return

	}

	key := parseKey{canon: canon, content: string(src), defaultYear: defaultYear}

	entry, ok := l.parseLookup(key)

	if !ok {

		lex := lexer.New(fpath, src)

		par := parser.NewWithYear(lex, defaultYear)

		j := par.ParseJournal()

		entry = parseEntry{src: src, ast: j}

		l.parseStore(key, entry)

	}

	pf := &ParsedFile{

		Path:   fpath,

		Src:    entry.src,

		Ast:    entry.ast,

		Errors: entry.ast.Errors,

	}

	rj.Occurrences = append(rj.Occurrences, pf)

	rj.ByPath[fpath] = append(rj.ByPath[fpath], pf)

	currentYear := defaultYear

	for i, entry := range entry.ast.Entries {

		switch e := entry.(type) {

		case *ast.BlankLine:

			continue

		case *ast.IncludeDirective:

			rj.Items = append(rj.Items, ResolvedItem{

				Occurrence: pf,

				IsInclude:  true,

				EntryIndex: i,

			})

			incPath, err := resolveIncludePath(fpath, e.Path)

			if err != nil {

				pf.FileErrors = append(pf.FileErrors, &ast.FileError{

					Path:    e.Path,

					Span:    e.Span,

					Message: err.Error(),

				})

				continue

			}

			matches, err := filepath.Glob(incPath)

			if err != nil || len(matches) == 0 {

				pf.FileErrors = append(pf.FileErrors, &ast.FileError{

					Path:    incPath,

					Span:    e.Span,

					Message: fmt.Sprintf("include not found: %s", e.Path),

				})

				continue

			}

			for _, match := range matches {

				childSrc, err := l.readContent(match)

				if err != nil {

					pf.FileErrors = append(pf.FileErrors, &ast.FileError{

						Path:    match,

						Span:    e.Span,

						Message: err.Error(),

					})

					continue

				}

				l.resolveOccurrence(rj, pf, match, childSrc, currentYear, append(stack, canon))

			}

		default:

			rj.Items = append(rj.Items, ResolvedItem{Occurrence: pf, EntryIndex: i})

		}

		// track year directive for context propagation to child includes

		if yd, ok := entry.(*ast.YearDirective); ok && yd.Year > 0 {

			currentYear = yd.Year

		}

	}

}

func resolveIncludePath(parentPath, incPattern string) (string, error) {

	base := filepath.Clean(filepath.Dir(parentPath))

	target := filepath.Clean(filepath.Join(base, incPattern))

	if filepath.IsAbs(incPattern) {

		return target, nil

	}

	// reject includes that escape the parent directory, e.g. "../../other.journal"

	rel, err := filepath.Rel(base, target)

	if err != nil || rel == ".." || strings.HasPrefix(rel, ".."+string(filepath.Separator)) {

		return "", fmt.Errorf("path traversal: %s", incPattern)

	}

	return target, nil

}

// CanonicalPath resolvea path to it's canonical form: absolute, symlinks evaluated, cleaned.

func CanonicalPath(path string) string {

	abs, err := filepath.Abs(path)

	if err != nil {

		return filepath.Clean(path)

	}

	canonical, err := filepath.EvalSymlinks(abs)

	if err != nil {

		return filepath.Clean(abs)

	}

	return filepath.Clean(canonical)

}

func (l *Loader) parseLookup(key parseKey) (parseEntry, bool) {

	l.mu.RLock()

	entry, ok := l.parseCache[key]

	l.mu.RUnlock()

	return entry, ok

}

func (l *Loader) parseStore(key parseKey, entry parseEntry) {

	l.mu.Lock()

	l.parseCache[key] = entry

	if len(l.parseCache) > parseCacheMax {

		for k := range l.parseCache {

			delete(l.parseCache, k)

			break

		}

	}

	l.mu.Unlock()

}