;license:MIT
;(c) 2018-2020 by 4am & qkumba
;
; text rank - an implementation of the Quicksilver search rank algorithm
;
; Public functions
; - BuildSearchStore
; - ResetTextRank
; - TextRankCallback (as okvs_iter_values callback)
;
; Public variables
; - InputLength                      ; [byte] number of characters typed in search mode
; - InputBuffer                      ; [25 bytes] characters typed in search mode
;
; Zero page variables
; - SelectedIndex                    ; [byte] index in gSearchStore of currently selected game in search mode
; - MatchCount                       ; [byte] number of games that match InputBuffer
; - BestMatchScore                   ; [byte] raw ranking score (0-100) of current best match (updated during TextRankCallback)
; - BestMatchIndex                   ; [byte] index in gSearchStore of current best match (updated during TextRankCallback)

MaxInputLength = 26
InputLength
         !byte 0
InputBuffer
         !text "                         "

;------------------------------------------------------------------------------
; BuildSearchStore
; Build a temporary data structure in main memory to support search UI.
; Now that gGamesListStore no longer contains full game display names, we call
; this to build a store that does. It's built in main memory and will be
; clobbered as soon as we enter attract mode (mega- or mini-), run a game,
; run a demo, or sneeze.
;
; in:    none
; out:   gSearchStore populated
;------------------------------------------------------------------------------
BuildSearchStore
         jsr   LoadFile              ; load appropriate search index into $8200
         !word kRootDirectory
         !word kSearchIndexFile
         !word $8200
         rts

;------------------------------------------------------------------------------
; ResetTextRank
; reset the Match variables to allow re-scanning (e.g. because of backspace)

; in:    nothing
; out:   X, MatchCount, BestMatchScore, BestMatchIndex zeroed
;------------------------------------------------------------------------------
ResetTextRank
         ldx   #0
         stx   MatchCount
         stx   BestMatchScore
         dex
         stx   BestMatchIndex
         stx   BestMatchIndex+1
         rts

;------------------------------------------------------------------------------
; TextRankCallback
; callback called by okvs_iter_values on gSearchStore
; to calculate a ranking score for a single game display name
; against the current InputBuffer

; in:    A/Y contains address of game display name
;        $WINDEX contains 0-based index of the current record in gSearchStore (word)
; out:   all registers and flags clobbered
;        MatchCount possibly incremented (if this game was a match at all)
;        BestMatchScore and BestMatchIndex possibly updated (if this game
;          was the best match so far)
;------------------------------------------------------------------------------
TextRankCallback
         +ST16 zpstring              ; A/Y = address of this game display name
         +LDADDR InputLength
         +ST16 zpword
         ldy   #0
         lda   (zpstring),y
         tax
         dex
         cpx   InputLength
         bcc   ++
         sta   gamelength
         sty   runningscore
         sty   runningscore+1
         iny
         sty   startat
-        sty   i
         lda   (zpword),y
         jsr   tolower
         sta   tmp
         ldy   startat
--       lda   (zpstring),y
         jsr   tolower
         cmp   tmp
         beq   +
         cpy   gamelength
         iny
         bcc   --
++       rts                         ; no match :(
+        ldx   #80
         cpy   startat
         beq   +
         ldx   #10
         cpy   #1
         beq   +
         dey
         lda   (zpstring),y
         iny
         cmp   #' '
         bne   +
         ldx   #90
+        txa
         clc
         adc   runningscore
         sta   runningscore
         bcc   +
         inc   runningscore+1
+        tya
         ldy   i
         cpy   InputLength
         bcs   +
         iny
         sta   startat
         inc   startat
         cmp   gamelength
         bcc   -
         rts                         ; no match :(
+        lda   runningscore
         ldx   runningscore+1
         ldy   gamelength
         jsr   @div
         sta   tmp
         lda   runningscore
         ldx   runningscore+1
         ldy   InputLength
         jsr   @div
         clc
         adc   tmp
         lsr
         adc   #0                    ; round fractions up
         pha
         ldy   #1
         lda   (zpstring),y
         jsr   tolower
         sta   firstletter
         pla
         ldx   InputBuffer
         cpx   firstletter
         bne   +
         cmp   #85
         bcs   +
         adc   #15
+        cmp   BestMatchScore
         bcc   +
         beq   +
         sta   BestMatchScore
         lda   WINDEX
         sta   BestMatchIndex
         lda   WINDEX+1
         sta   BestMatchIndex+1
         inc   MatchCount
+        rts

@div
         sta   num1
         stx   num1+1
         sty   num2
         lda   #0
         sta   remainder
         sta   remainder+1
         ldx   #16
-        asl   num1
         rol   num1+1
         rol   remainder
         rol   remainder+1
         lda   remainder
         sec
         sbc   num2
         bcc   +
         sta   remainder
         dec   remainder+1
         inc   num1
+        dex
         bne   -
         lda   num1
         rts

tolower
         cmp   #$41
         bcc   +
         cmp   #$5B
         bcs   +
         ora   #$20
+        rts