Create a program to turn MML strings into custom text strings

literally take a string of text (MML) and run it through said program example being t104v9cl8<gab+4gal4.>fgl16<gal8gb+[login to view URL]>f4.d2&d>[login to view URL]<gl16gag8gag8>[login to view URL]<ab8gb8b+8g4.>[login to view URL]<agf4ag>ecl16<gag8gag8>[login to view URL]<ab8gl8bb+g4.>gggf4ecc16d.e4g4.ral16ge8d4&d<g8ab+[login to view URL]>cdc2&c8r8.gg8g4f4e8c8cd8.e4g4.r8a8ge8d4&d<g8ab+[login to view URL]>cdc2&c8r8a8ge8d4&d<g8a>c2&cr8<a8>cdc2&c8<a8a>c8dc8<f8ga8b+a8g8ga8bg8c8g>c8dc8<<a8>a>c8dc8<f8ga8b+a8<g8>ga8bg8g4>[login to view URL]<gl16gag8gag8>[login to view URL]<ab8ab8b+8g4.>[login to view URL]<agf4ag>ecl16<gag8gag8>[login to view URL]<ab8gb8b+8g4>ggg8g4f4e8c8c+d8.e4g4.r8a8ge8d4&d<g8ab+[login to view URL]>cdc2&c8r8ggg8g4f4e8c8c+d8.e4g4.r8a8ge8d4&d<g8ab+[login to view URL]>cdc2&c8<c8g>c8dc8<<a8>a>c8dc8<f8ga8b+a8<g8>ga8bg8c8g>c8dc8<<a8>a>c8dc8<f8a>[login to view URL]<gge>[login to view URL]<ag4fa>gefdecd<g>afgefdecl2cdfgr8l16ggg8g4f4e8c8c+d8.e4g4.r8a8ge8d4&d<g8ab+[login to view URL]>cdc2&c8r8ggg8g4f4e8c8c+d8.e4g4.r8a8ge8d4&d<g8ab+[login to view URL]>cdc4.<g8a>cc8<a8>cdc4.<g8a>cf8ec8<ab+4g4.l8gefc4a4g2&grga>c16c1&c16gefdecd<gc4ggg4.l16gfe8fgl8abg.b.g>c1; have it remove any text that isn't "a" "b" "c" "d" "e" "f" "g" "<" ">" "-" and "+" to end up with this c<gab+ga>fg<gagb+gaga>fd>cggggfeefgedcdec<ggaggag>cc<abgbb+g>gagefgfed<agfag>ec<gaggag>cc<abgbb+g>gggfeccdegagedd<gab+a>cdccgggfeccdegagedd<gab+a>cdccagedd<ga>cc<a>cdcc<aa>cdc<fgab+aggabgcg>cdc<<a>a>cdc<fgab+a<g>gabgg>ggggfeefgedcdec<ggaggag>cc<ababb+g>gagefgfed<agfag>ec<gaggag>cc<abgbb+g>ggggfecc+degagedd<gab+a>cdccggggfecc+degagedd<gab+a>cdcc<cg>cdc<<a>a>cdc<fgab+a<g>gabgcg>cdc<<a>a>cdc<fa>dfggggfeefgedcdgefdecd<gge>daggagefgfed<agfa>gefdecd<g>afgefdeccdfgggggfecc+degagedd<gab+a>cdccggggfecc+degagedd<gab+a>cdc<ga>cc<a>cdc<ga>cfec<ab+ggefcaggga>cccgefdecd<gcggggfefgabgbg>c . then have the program recognize what octave the string starts in or have it let you choose (for the specific use I have for this, I need exactly three octaves, and then one note from a 4th, highest octave. Only 37 notes have it let you input a keybind for all 37 possible notes- Note, in this keybind example, all keys to the right of " : " should be customizable to the user. All to the left of " : " are note and octave variants of a-g. "-", "+", and the lack of either determines which octave the note is in. " - " being the lower of the three, " + " being the higher of the three, and the lack of either being the middle octave. C+2 is the only exception, being that it is the highest note, alone in its own octave. Also note, in MML strings and music in general, B+ (b sharp) is up an octave C, and C- (c flat) is down an octave B, and should be programmed to be read as so C-1 : 1 C#-1 : 2 D-1 : 3 Eb-1 : 4 E-1 : 5 F-1 : 6 F#-1 : 7 G-1 : 8 G#-1 : 9 A-1 : 0 Bb-1 : - B-1 : = C : Q C# : W D : E Eb : R E : T F : Y F# : U G : I G# : O A : P Bb : [ B : ] C+1 : A C#+1 : S D+1 : D Eb+1 : F E+1 : G F+1 : H F#+1 : J G+1 : K G#+1 : L A+1 : ; Bb+1 : ' B+1 : Z C+2 : X once it knows which of 3 octaves (or c+2) the MML string starts in, have it translate all instances of "a" through "g" with its corresponding keybind. I only know the very basics of programming, but I believe the easiest way to accomplish this is have it recognize whether the first note is in the lower, middle, higher octave or c+2 from there, all instances of ">" or "<" changes all subsequent instances of "a" through "g" into its "a-g -1", "a-g", "a-g +1", and "c+2" counterparts, until the next ">" or "<", where it then continues. and then it's an easy translate (example) "F+1" into whatever F+1 is bound to (in previous example, it's bound to " H " this SHOULD, in theory, turn the beginning of our original MML string into this. q80q80yi808q8080yeakkkkhgghkgdadgaiipiipiaap]i]aik;kghkhgdpiypigaipiipiaap]i]ai (price range is negotiable, though I'd like to talk about a few of the ins and outs if you think you can manage this, to better price for both of us ^^)