Convert BTC to STX address

(define-read-only (btc-to-stx (input (string-ascii 60)))
  (let (
    ;; Decode base58 string to numbers
    (b58-numbers (map unwrap-uint (filter is-some-uint (map b58-to-uint input))))
    ;; Validate all characters are valid base58
    (t1 (asserts! (>= (len b58-numbers) (len input)) ERR_INVALID_CHAR))
    ;; Count leading '1's (zeros in base58)
    (leading-ones-count (default-to (len input) (index-of? (map is-zero b58-numbers) false)))
    ;; Convert to bytes
    (decoded (concat (fold decode-outer to-decode LST) leading-zeros))
    (decoded-hex (fold to-hex-rev decoded 0x))
    ;; Verify checksum
    (actual-checksum (unwrap-panic (slice? (sha256 (sha256 (unwrap-panic (slice? decoded-hex u0 (- decoded-hex-len u4))))) u0 u4)))
    (expected-checksum (unwrap-panic (slice? decoded-hex (- decoded-hex-len u4) decoded-hex-len)))
    (t3 (asserts! (is-eq actual-checksum expected-checksum) ERR_BAD_CHECKSUM))
    ;; Extract version and construct principal
    (version (unwrap-panic (element-at? STX_VER (unwrap! (index-of? BTC_VER (unwrap-panic (element-at? decoded-hex u0))) ERR_INVALID_VERSION))))
    )
    (principal-construct? version (unwrap-panic (as-max-len? (unwrap-panic (slice? decoded-hex u1 (- decoded-hex-len u4))) u20)))
  )
)

;; Example usage
(btc-to-stx "1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa") ;; Returns Stacks address

;; Constants for base58 alphabet and version mappings
(define-constant BASE58_CHARS "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz")
(define-constant STX_VER 0x16141a15)
(define-constant BTC_VER 0x00056fc4)
(define-constant ALL_HEX 0x000102...FF) ;; All hex values 0-255

;; Error constants
(define-constant ERR_INVALID_CHAR (err u1001))
(define-constant ERR_TOO_SHORT (err u1002))
(define-constant ERR_BAD_CHECKSUM (err u1003))
(define-constant ERR_INVALID_VERSION (err u1004))

;; Helper functions
(define-read-only (b58-to-uint (x (string-ascii 1))) 
  (index-of? BASE58_CHARS x))

(define-read-only (is-some-uint (x (optional uint))) 
  (is-some x))

(define-read-only (unwrap-uint (x (optional uint))) 
  (unwrap-panic x))

;; Base conversion logic
(define-read-only (decode-outer (x uint) (out (list 33 uint)))
  (let (
    (new-out (fold update-out out (list x)))
    (carry-to-push (fold carry-push 0x0000 (list (unwrap-panic (element-at? new-out u0)))))
    )
    (concat
      (default-to (list) (slice? new-out u1 (len new-out)))
      (default-to (list) (slice? carry-to-push u1 (len carry-to-push)))
    )
  )
)

;; Test with known Bitcoin addresses
(btc-to-stx "1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa") ;; Satoshi's address
(btc-to-stx "3J98t1WpEZ73CNmQviecrnyiWrnqRhWNLy") ;; P2SH address
(btc-to-stx "1CounterpartyXXXXXXXXXXXXXXXUWLpVr") ;; Counterparty burn