#lang racket/base

(require racket/cmdline
         racket/file
         racket/list
         racket/path
         "private/audio.rkt"
         "private/config.rkt"
         "private/convert-place.rkt"
         "private/cover-art.rkt"
         "private/fingerprint.rkt"
         "private/hash.rkt"
         "private/log.rkt"
         "private/mail.rkt"
         "private/report.rkt"
         "private/scan.rkt"
         "private/state.rkt"
         "private/util.rkt")

(provide manage-flac-tree
         summary->lines)

(define (quick-file-info path)
  (list (cons 'size (file-size path))
        (cons 'mtime (file-or-directory-modify-seconds path))))

(define (same-quick-state? old path)
  (and old
       (equal? (alist-ref/default old 'size #f) (file-size path))
       (equal? (alist-ref/default old 'mtime #f) (file-or-directory-modify-seconds path))
       (not (equal? (alist-ref/default old 'status #f) 'error))))

(define (same-signature-state? old signature)
  (and old
       (equal? (alist-ref/default old 'signature #f) signature)
       (not (equal? (alist-ref/default old 'status #f) 'error))))

(define (file-signature path config fingerprint-proc)
  (define mode (manager-config-change-detection config))
  (cond [(member mode '("hash" "sha256" "full-hash" "full-sha256"))
         (string-append "file:"
                        (manager-config-hash-algorithm config)
                        ":"
                        (file-digest path (manager-config-hash-algorithm config)))]
        [(member mode '("mtime-size" "quick"))
         (format "mtime-size:~a:~a" (file-size path) (file-or-directory-modify-seconds path))]
        [(member mode '("flac" "flac-streaminfo"))
         (string-append "flac-streaminfo:" (flac-streaminfo-fingerprint path))]
        [(or (member mode '("flac-taglib" "taglib+flac" "taglib-flac")) (not mode))
         (string-append "flac-taglib:" (fingerprint-proc path))]
        [else
         (error 'file-signature "unsupported change-detection mode: ~a" mode)]))

(define (state-info path signature status sample-rate extra)
  (append (quick-file-info path)
          (list (cons 'signature signature)
                (cons 'status status)
                (cons 'sample-rate sample-rate))
          extra))

(define (maybe-set-sidecar-picture! path relpath)
  (with-handlers ([exn:fail? (lambda (e)
                               (warn-alm "could not set sidecar cover for ~a: ~a" relpath (exn-message e))
                               #f)])
    (define cover (ensure-flac-sidecar-picture! path))
    (when cover (info-alm "embedded sidecar cover in ~a from ~a" relpath cover))
    cover))

(define (process-one-file ks config path relpath inspect-flac-proc fingerprint-proc convert-proc summary errors)
  ;; Only invokes TagLib when a sidecar cover/folder image exists in the same directory.
  ;; This keeps the cheap mtime/size fast path cheap for most directories, but still
  ;; lets the manager repair missing embedded artwork before fingerprinting.
  (maybe-set-sidecar-picture! path relpath)
  (define old (state-get-file ks relpath #f))
  (cond [(same-quick-state? old path)
         (info-alm "unchanged: ~a" relpath)
         (values (summary-inc (summary-inc summary 'seen) 'unchanged) errors)]
        [else
         (define summary1 (summary-inc (summary-inc summary 'seen) 'processed))
         (define summary2 (if old (summary-inc summary1 'changed) (summary-inc summary1 'new)))
         (with-handlers ([exn:fail?
                          (lambda (e)
                            (err-alm "error for ~a: ~a" relpath (exn-message e))
                            (state-set-file! ks relpath
                                             (append (quick-file-info path)
                                                     (list (cons 'status 'error)
                                                           (cons 'message (exn-message e)))))
                            (values (summary-inc summary2 'errors)
                                    (cons (list (cons 'file relpath)
                                                (cons 'message (exn-message e)))
                                          errors)))])
           (define sample-rate (inspect-flac-proc path))
           (define signature (file-signature path config fingerprint-proc))
           (cond [(same-signature-state? old signature)
                  (info-alm "unchanged fingerprint: ~a" relpath)
                  (state-set-file! ks relpath (state-info path signature 'unchanged sample-rate '()))
                  (values (summary-inc summary2 'unchanged) errors)]
                 [(> sample-rate (manager-config-max-sample-rate config))
                  (if (manager-config-dry-run? config)
                      (begin
                        (warn-alm "dry-run: would convert ~a from ~a Hz to ~a Hz" relpath sample-rate (manager-config-max-sample-rate config))
                        (state-set-file! ks relpath
                                         (state-info path signature 'dry-run sample-rate '()))
                        (values (summary-inc (summary-inc summary2 'skipped) 'dry-run) errors))
                      (begin
                        (info-alm "converting ~a from ~a Hz to ~a Hz" relpath sample-rate (manager-config-max-sample-rate config))
                        (let* ((result (convert-proc path
                                                     (manager-config-max-sample-rate config)
                                                     (manager-config-compression-level config)))
                               (new-sample-rate (inspect-flac-proc path))
                               (new-signature (file-signature path config fingerprint-proc)))
                          (state-set-file! ks relpath
                                           (state-info path new-signature 'converted new-sample-rate
                                                       (list (cons 'old-sample-rate sample-rate)
                                                             (cons 'encoder-result result))))
                          (values (summary-inc summary2 'converted) errors))))]
                 [else
                  (info-alm "ok: ~a (~a Hz)" relpath sample-rate)
                  (state-set-file! ks relpath (state-info path signature 'ok sample-rate '()))
                  (values (summary-inc summary2 'ok) errors)]))]))

(define (drop-removed! ks current-relpaths summary)
  (define current (for/hash ([r (in-list current-relpaths)]) (values r #t)))
  (for/fold ([s summary]) ([old-rel (in-list (state-known-relpaths ks))])
    (if (hash-ref current old-rel #f)
        s
        (begin
          (info-alm "removed from state: ~a" old-rel)
          (state-drop-file! ks old-rel)
          (summary-inc s 'removed)))))

(define (manage-flac-tree base-directory
                          #:inspect-flac-proc [inspect-flac-proc inspect-flac-sample-rate]
                          #:fingerprint-proc [fingerprint-proc flac-taglib-fingerprint]
                          #:convert-proc [convert-proc convert-flac-to-target-in-place])
  (define base-dir (filesystem-path base-directory))
  (unless (directory-exists? base-dir)
    (raise-argument-error 'manage-flac-tree "existing directory" base-directory))
  (define config (load-manager-config base-dir))
  (setup-logging! (manager-config-log-file config) (manager-config-display-log? config))
  (info-alm "base directory: ~a" base-dir)
  (info-alm "state file: ~a" (manager-config-state-file config))
  (info-alm "ini file: ~a" (manager-config-ini-file config))
  (info-alm "change detection: ~a" (manager-config-change-detection config))
  (define ks (open-manager-state (manager-config-state-file config)))
  (define files (find-flac-files base-dir))
  (define relpaths (map (lambda (p) (relpath-string base-dir p)) files))
  (define summary0 (drop-removed! ks relpaths (make-empty-summary)))
  (define-values (summary errors)
    (for/fold ([summary summary0] [errors '()]) ([p (in-list files)] [rel (in-list relpaths)])
      (process-one-file ks config p rel inspect-flac-proc fingerprint-proc convert-proc summary errors)))
  (define errors* (reverse errors))
  (with-handlers ([exn:fail? (lambda (e) (err-alm "mail report failed: ~a" (exn-message e)) (void))])
    (maybe-send-report-mail config summary errors*))
  (for ([line (in-list (summary->lines summary))]) (info-alm "summary: ~a" line))
  summary)

(module+ main
  (define base-dir #f)
  (command-line
   #:program "flac-48khz-manager.rkt"
   #:args (base-directory)
   (set! base-dir base-directory))
  (define summary (manage-flac-tree base-dir))
  (for ([line (in-list (summary->lines summary))])
    (displayln line)))