#[Copyright 2023 ITwrx.
This file is part of EZ-Bkup.
EZ-Bkup is released under the General Public License 3.0.
See COPYING or <https://www.gnu.org/licenses/> for details.]#

import std/[tables, strutils, sugar, hashes, algorithm, os]
from std/sequtils import toSeq
import tiny_sqlite
import "../shared"

# We create a custom type for representing the ID of a routine.
# This way Nim's type system automatically prevents us from using it as a regular integer and
# from confusing it with the ID of another entity.

type RoutineId* = distinct int64

proc `==`*(a, b: RoutineId): bool {.borrow.}
proc hash*(id: RoutineId): Hash {.borrow.}
proc `$`*(id: RoutineId): string =
  result = "routine" & $int64(id)

type Routine* = object
  id*: RoutineId
  name*: string
  selected*: bool
  #selected by default.
  selByDef*: bool
  sources*: seq[string]
  destinations*: seq[string] 

proc stringToSeq(commaSepString: string):seq[string] =
  var newSeq: seq[string]
  if hasCommas(commaSepString) == true:
    newSeq = toSeq(commaSepString.split(','))
  else:    
    newSeq = @[commaSepString]
  
  return newSeq
  
proc seqToString(strSeq: seq[string]):string =
  var newStr: string
  if strSeq.len >= 1:
    newStr = strSeq.join(",")
  else:
    newStr = ""

  return newStr 

proc locationsExist*(routine: Routine): bool =
  var logMsg: string
  var exists: seq[int]
  for source in routine.sources:
    if dirExists(source) or fileExists(source):
      exists.add(1)
    else:
      logMsg = "(" & nowDT & ")" & " Source not found: " & source 
      writeErrorToLog(logMsg)
      exists.add(0)

  for dest in routine.destinations:
    if dirExists(dest) or fileExists(dest):
      exists.add(1)
    else:
      logMsg = "(" & nowDT & ")" & " Destination not found: " & dest 
      writeErrorToLog(logMsg)
      exists.add(0)

  if 0 in exists:
    return false
  else:
    return true

type RoutineModel* = ref object
  ## Model for storing all routines. We model this as a ref object, so that changes
  ## made by any widget are also known to all other widgets that use the model.
  
  db: DbConn
  routines*: Table[RoutineId, Routine]

proc cmpRoutines(a, b: Routine): int =
  cmp(a.name, b.name)


#returns a seq so we can iterate in routine_list.
proc routineSeq*(model: RoutineModel): seq[Routine] =
  var routineSeq: seq[Routine]
  ## Returns a seq of all routines. "id" is necessary to loop through table.
  for id, routine in model.routines:
      routineSeq.add(routine)

  routineSeq.sort(cmpRoutines, Ascending)

  return routineSeq

let homePath = expandTilde("~")

proc newRoutineModel*(path: string = homePath & "/.ez-bkup/ez-bkup.sqlite"): RoutineModel =
  ## Load a RoutineModel from a database
  
  var db: DbConn
  try:  
    db = openDatabase(path)
  except:    
    writeErrorToLog("Unable to open and/or create sqlite3 database. Please make sure sqlite3 is installed.")
    db = openDatabase("")

  # Create the Routine table
  db.exec("""
    CREATE TABLE IF NOT EXISTS Routine(
      id INTEGER PRIMARY KEY,
      name TEXT,
      selByDef INTEGER,
      sources TEXT,
      destinations TEXT
    )
  """)
  
  # Load all existing routines into RoutineModel.routines
  var routines = initTable[RoutineId, Routine]()
  for row in db.iterate("SELECT id, name, selByDef, sources, destinations FROM Routine"):
    let (id, name, selByDef, sources, destinations) = row.unpack((RoutineId, string, bool, string, string))

    var sourcesSeq: seq[string]    
    #no sources exist in DB.
    if sources == "":
      sourcesSeq = @[]
    else:
      #convert "sources" comma-separated string to seq[string].
      sourcesSeq = stringToSeq(sources)

    var destinationsSeq: seq[string]    
    #no destinations exist in DB.
    if destinations == "":
      destinationsSeq = @[]
    else:
      #convert "destinations" comma-separated string to seq[string].
      destinationsSeq = stringToSeq(destinations)

    routines[id] = Routine(id: id, name: name, selByDef: selByDef, sources: sourcesSeq, destinations: destinationsSeq)
  
  result = RoutineModel(db: db, routines: routines)

proc add*(model: RoutineModel, routine: Routine) =
  ## Adds a new routine to the model

  #convert routine.sources seq[string] to a comma-separated string to store as TEXT in sqlite.
  let stringSources = seqToString(routine.sources)

  #convert routine.destinations seq[string] to a comma-separated string to store as TEXT in sqlite.
  let stringDestinations = seqToString(routine.destinations)
  
  # Insert new routine into database
  model.db.exec(
    "INSERT INTO Routine (name, selByDef, sources, destinations) VALUES (?, ?, ?, ?)",
    routine.name, routine.selByDef, stringSources, stringDestinations
  )
  
  # Insert new routine into RoutineModel.routines
  let id = RoutineId(model.db.lastInsertRowId)
  model.routines[id] = routine.dup(id = id)

proc update*(model: RoutineModel, routine: Routine) =
  ## Updates an existing routine. Routines are compared by their ID.

  #convert routine.sources seq[string] to a comma-separated string to store as TEXT in sqlite.
  let stringSources = seqToString(routine.sources)

  #convert routine.destinations seq[string] to a comma-separated string to store as TEXT in sqlite.
  let stringDestinations = seqToString(routine.destinations)
  
  # Update routine in database
  model.db.exec(
    "UPDATE Routine SET name = ?, selByDef = ?, sources = ?, destinations = ? WHERE id = ?",
    routine.name, routine.selByDef, stringSources, stringDestinations, routine.id  
  )
  
  # Update RoutineModel.routines
  model.routines[routine.id] = routine

proc delete*(model: RoutineModel, id: RoutineId) =
  ## Deletes the routine with the given ID
  
  # Delete routine from database
  model.db.exec("DELETE FROM Routine WHERE id = ?", id)
  
  # Update RoutineModel.routines
  model.routines.del(id)

#preload the selected seq with routines that have selByDef == true.
proc selectedPreload*(): seq[RoutineId] =
  var selected: seq[RoutineId]
  let model = newRoutineModel(databasePath)
  for routine in model.routineSeq():
    if routine.selByDef == true:
      selected.add(routine.id)
  return selected