! Layer 15 — Sovereign IDE Application Shell
! Session state, workspace, main event loop, BOB context slot
! Maps to: bob-ide, bob-orchestrator
MODULE sovereign_shell
  USE iso_c_binding
  USE sovereign_runtime, ONLY: runtime_init, runtime_teardown, runtime_panic, str_intern
  IMPLICIT NONE
  PRIVATE

  ! ── Workspace descriptor ─────────────────────────────────────────────────
  INTEGER, PARAMETER :: MAX_OPEN_FILES = 512
  INTEGER, PARAMETER :: MAX_PANELS     = 16

  TYPE :: panel_t
    REAL    :: x = 0.0, y = 0.0, w = 1.0, h = 1.0
    INTEGER :: buffer_idx = 0
    LOGICAL :: active     = .FALSE.
  END TYPE panel_t

  TYPE :: workspace_t
    INTEGER(C_INT32_T) :: root_path_id     = 0
    INTEGER(C_INT32_T) :: open_files(MAX_OPEN_FILES)
    INTEGER            :: open_count       = 0
    TYPE(panel_t)      :: panels(MAX_PANELS)
    INTEGER            :: panel_count      = 1
    INTEGER            :: active_panel     = 1
    LOGICAL            :: dirty            = .FALSE.
  END TYPE workspace_t

  ! ── Session state (WORM-sealed) ──────────────────────────────────────────
  TYPE :: session_t
    TYPE(workspace_t)  :: workspace
    INTEGER(C_INT64_T) :: frame_count     = 0
    LOGICAL            :: bob_context_loaded = .FALSE.
    INTEGER(C_INT32_T) :: session_id      = 0
    LOGICAL            :: running         = .FALSE.
  END TYPE session_t

  TYPE(session_t), SAVE :: g_session

  PUBLIC :: shell_init
  PUBLIC :: shell_run
  PUBLIC :: shell_shutdown
  PUBLIC :: shell_open_file
  PUBLIC :: shell_close_file
  PUBLIC :: shell_split_panel
  PUBLIC :: shell_save_session
  PUBLIC :: shell_restore_session

CONTAINS

  ! ---------------------------------------------------------------------------
  SUBROUTINE shell_init(workspace_root)
    CHARACTER(LEN=*), INTENT(IN) :: workspace_root
    CALL runtime_init()
    g_session%workspace%root_path_id = str_intern(workspace_root)
    g_session%workspace%panel_count  = 1
    g_session%workspace%active_panel = 1
    g_session%workspace%panels(1)%active = .TRUE.
    g_session%running = .TRUE.
    g_session%frame_count = 0
    WRITE(*,'(A,A)') '[shell] init workspace: ', TRIM(workspace_root)
  END SUBROUTINE shell_init

  ! ---------------------------------------------------------------------------
  ! Main event loop: poll → update → render → repeat
  SUBROUTINE shell_run()
    DO WHILE (g_session%running)
      g_session%frame_count = g_session%frame_count + 1
      ! 1. Poll OS events (Layer 1 platform)
      ! TODO: CALL platform_poll_events()
      ! 2. Process input (Layer 2 GUI input dispatch)
      ! TODO: CALL gui_process_input()
      ! 3. Update all active layers
      ! TODO: CALL lsp_tick()      — Layer 12
      ! TODO: CALL dap_tick()      — Layer 13
      ! TODO: CALL ext_host_tick() — Layer 14
      ! 4. Begin frame (Layer 2 GUI)
      ! TODO: CALL gui_begin_frame()
      ! 5. Render panels → text buffers → syntax highlighting
      ! TODO: CALL gui_render_panels()
      ! 6. End frame
      ! TODO: CALL gui_end_frame()
      ! 7. Auto-save session every 300 frames
      IF (MOD(g_session%frame_count, 300) == 0) CALL shell_save_session()
      ! Stub: exit after first frame for now
      g_session%running = .FALSE.
    END DO
  END SUBROUTINE shell_run

  ! ---------------------------------------------------------------------------
  SUBROUTINE shell_shutdown()
    CALL shell_save_session()
    ! Teardown in reverse order: 15 → 0
    ! TODO: CALL ext_host_shutdown()  — Layer 14
    ! TODO: CALL dap_shutdown()       — Layer 13
    ! TODO: CALL lsp_shutdown()       — Layer 12
    ! TODO: CALL build_shutdown()     — Layer 11
    ! ...
    CALL runtime_teardown()
    WRITE(*,'(A,I0,A)') '[shell] shutdown after ', g_session%frame_count, ' frames'
  END SUBROUTINE shell_shutdown

  ! ---------------------------------------------------------------------------
  SUBROUTINE shell_open_file(path)
    CHARACTER(LEN=*), INTENT(IN) :: path
    INTEGER(C_INT32_T) :: fid
    IF (g_session%workspace%open_count >= MAX_OPEN_FILES) &
      CALL runtime_panic('shell_open_file: too many open files')
    fid = str_intern(path)
    g_session%workspace%open_count = g_session%workspace%open_count + 1
    g_session%workspace%open_files(g_session%workspace%open_count) = fid
    g_session%workspace%dirty = .TRUE.
    WRITE(*,'(A,A)') '[shell] opened: ', TRIM(path)
  END SUBROUTINE shell_open_file

  ! ---------------------------------------------------------------------------
  SUBROUTINE shell_close_file(idx)
    INTEGER, INTENT(IN) :: idx
    INTEGER :: i
    IF (idx < 1 .OR. idx > g_session%workspace%open_count) RETURN
    DO i = idx, g_session%workspace%open_count - 1
      g_session%workspace%open_files(i) = g_session%workspace%open_files(i+1)
    END DO
    g_session%workspace%open_count = g_session%workspace%open_count - 1
    g_session%workspace%dirty = .TRUE.
  END SUBROUTINE shell_close_file

  ! ---------------------------------------------------------------------------
  SUBROUTINE shell_split_panel(direction)
    CHARACTER(LEN=*), INTENT(IN) :: direction
    INTEGER :: n
    n = g_session%workspace%panel_count
    IF (n >= MAX_PANELS) RETURN
    g_session%workspace%panel_count = n + 1
    g_session%workspace%panels(n+1)%active = .TRUE.
    IF (direction == 'v') THEN
      g_session%workspace%panels(n)%w   = g_session%workspace%panels(n)%w * 0.5
      g_session%workspace%panels(n+1)%x = g_session%workspace%panels(n)%x + g_session%workspace%panels(n)%w
      g_session%workspace%panels(n+1)%w = g_session%workspace%panels(n)%w
    ELSE
      g_session%workspace%panels(n)%h   = g_session%workspace%panels(n)%h * 0.5
      g_session%workspace%panels(n+1)%y = g_session%workspace%panels(n)%y + g_session%workspace%panels(n)%h
      g_session%workspace%panels(n+1)%h = g_session%workspace%panels(n)%h
    END IF
    g_session%workspace%dirty = .TRUE.
  END SUBROUTINE shell_split_panel

  ! ---------------------------------------------------------------------------
  ! Session save: serialize workspace to WORM-sealed JSON
  SUBROUTINE shell_save_session()
    IF (.NOT. g_session%workspace%dirty) RETURN
    ! TODO: serialize workspace_t → JSON
    ! TODO: CALL bifrost_worm_append(session_json)  — Layer 0 WORM
    g_session%workspace%dirty = .FALSE.
    WRITE(*,'(A,I0)') '[shell] session saved at frame ', g_session%frame_count
  END SUBROUTINE shell_save_session

  ! ---------------------------------------------------------------------------
  SUBROUTINE shell_restore_session(session_path)
    CHARACTER(LEN=*), INTENT(IN) :: session_path
    ! TODO: read WORM-sealed session file
    ! TODO: deserialize → workspace_t
    ! TODO: re-open all files (Layer 3 buffer restore)
    ! TODO: reconnect BOB context (Layer 14 ext_host_connect_bob)
    g_session%bob_context_loaded = .TRUE.
    WRITE(*,'(A,A)') '[shell] restored session: ', TRIM(session_path)
  END SUBROUTINE shell_restore_session

END MODULE sovereign_shell