(defvar hl-bigrams
  (list "aa" "ab" "ac" "ad" "ae" "af" "ag" "ah" "ai" "aj" "ak" "al" "am" "an"
	"ao" "ap" "aq" "ar" "as" "at" "au" "av" "aw" "ax" "ay" "az" "ba" "bb"
	"bc" "bd" "be" "bf" "bg" "bh" "bi" "bj" "bk" "bl" "bm" "bn" "bo" "bp"
	"br" "bs" "bt" "bu" "bv" "bw" "bx" "by" "bz" "ca" "cb" "cc" "cd" "ce"
	"cf" "cg" "ch" "ci" "cj" "ck" "cl" "cm" "cn" "co" "cp" "cq" "cr" "cs"
	"ct" "cu" "cv" "cw" "cx" "cy" "cz" "da" "db" "dc" "dd" "de" "df" "dg"
	"dh" "di" "dj" "dk" "dl" "dm" "dn" "do" "dp" "dq" "dr" "ds" "dt" "du"
	"dv" "dw" "dx" "dy" "dz" "ea" "eb" "ec" "ed" "ee" "ef" "eg" "eh" "ei"
	"ej" "ek" "el" "em" "en" "eo" "ep" "eq" "er" "es" "et" "eu" "ev" "ew"
	"ex" "ey" "ez" "fa" "fb" "fc" "fd" "fe" "ff" "fg" "fh" "fi" "fj" "fk"
	"fl" "fm" "fn" "fo" "fp" "fq" "fr" "fs" "ft" "fu" "fv" "fw" "fx" "fy"
	"fz" "ga" "gb" "gc" "gd" "ge" "gf" "gg" "gh" "gi" "gj" "gl" "gm" "gn"
	"go" "gp" "gr" "gs" "gt" "gu" "gv" "gw" "gx" "gy" "gz" "ha" "hb" "hc"
	"hd" "he" "hf" "hg" "hh" "hi" "hj" "hk" "hl" "hm" "hn" "ho" "hp" "hq"
	"hr" "hs" "ht" "hu" "hv" "hw" "hx" "hy" "hz" "ia" "ib" "ic" "id" "ie"
	"if" "ig" "ih" "ii" "ij" "ik" "il" "im" "in" "io" "ip" "iq" "ir" "is"
	"it" "iu" "iv" "iw" "ix" "iy" "iz" "ja" "jb" "jc" "jd" "je" "jf" "jg"
	"jh" "ji" "jj" "jk" "jl" "jm" "jn" "jo" "jp" "jq" "jr" "js" "jt" "ju"
	"jw" "jx" "jy" "ka" "kb" "kc" "kd" "ke" "kf" "kg" "kh" "ki" "kj" "kk"
	"kl" "km" "kn" "ko" "kp" "kr" "ks" "kt" "ku" "kv" "kw" "kx" "ky" "la"
	"lb" "lc" "ld" "le" "lf" "lg" "lh" "li" "lj" "lk" "ll" "lm" "ln" "lo"
	"lp" "lr" "ls" "lt" "lu" "lv" "lw" "lx" "ly" "lz" "ma" "mb" "mc" "md"
	"me" "mf" "mg" "mh" "mi" "mj" "mk" "ml" "mm" "mn" "mo" "mp" "mq" "mr"
	"ms" "mt" "mu" "mv" "mw" "mx" "my" "mz" "na" "nb" "nc" "nd" "ne" "nf"
	"ng" "nh" "ni" "nj" "nk" "nl" "nm" "nn" "no" "np" "nr" "ns" "nt" "nu"
	"nv" "nw" "nx" "ny" "nz" "oa" "ob" "oc" "od" "oe" "of" "og" "oh" "oi"
	"oj" "ok" "ol" "om" "on" "oo" "op" "oq" "or" "os" "ot" "ou" "ov" "ow"
	"ox" "oy" "oz" "pa" "pb" "pc" "pd" "pe" "pf" "pg" "ph" "pi" "pj" "pk"
	"pl" "pm" "pn" "po" "pp" "pq" "pr" "ps" "pt" "pu" "pv" "pw" "px" "py"
	"pz" "qa" "qb" "qc" "qd" "qe" "qh" "qi" "ql" "qm" "qn" "qo" "qp" "qq"
	"qr" "qs" "qt" "qu" "qw" "qx" "qy" "ra" "rb" "rc" "rd" "re" "rf" "rg"
	"rh" "ri" "rk" "rl" "rm" "rn" "ro" "rp" "rq" "rr" "rs" "rt" "ru" "rv"
	"rw" "rx" "ry" "rz" "sa" "sb" "sc" "sd" "se" "sf" "sg" "sh" "si" "sj"
	"sk" "sl" "sm" "sn" "so" "sp" "sq" "sr" "ss" "st" "su" "sv" "sw" "sx"
	"sy" "sz" "ta" "tb" "tc" "td" "te" "tf" "tg" "th" "ti" "tj" "tk" "tl"
	"tm" "tn" "to" "tp" "tr" "ts" "tt" "tu" "tv" "tw" "tx" "ty" "tz" "ua"
	"ub" "uc" "ud" "ue" "uf" "ug" "uh" "ui" "uj" "uk" "ul" "um" "un" "uo"
	"up" "uq" "ur" "us" "ut" "uu" "uv" "uw" "ux" "uy" "uz" "va" "vb" "vc"
	"vd" "ve" "vf" "vg" "vh" "vi" "vj" "vk" "vl" "vm" "vn" "vo" "vp" "vq"
	"vr" "vs" "vt" "vu" "vv" "vw" "vx" "vy" "vz" "wa" "wb" "wc" "wd" "we"
	"wf" "wg" "wh" "wi" "wj" "wk" "wl" "wm" "wn" "wo" "wp" "wr" "ws" "wt"
	"wu" "wv" "ww" "wx" "wy" "xa" "xb" "xc" "xd" "xe" "xf" "xh" "xi" "xl"
	"xm" "xn" "xo" "xp" "xr" "xs" "xt" "xu" "xx" "xy" "xz" "ya" "yb" "yc"
	"yd" "ye" "yf" "yg" "yh" "yi" "yj" "yk" "yl" "ym" "yn" "yo" "yp" "yr"
	"ys" "yt" "yu" "yv" "yw" "yx" "yy" "yz" "za" "zb" "zc" "zd" "ze" "zf"
	"zg" "zh" "zi" "zk" "zl" "zm" "zn" "zo" "zp" "zr" "zs" "zt" "zu" "zw"
	"zx" "zy" "zz")
  "List of bigrams for use with hashline reads/writes.

Each of the bigrams resolve to a single token in standard LLM
vocabulary, unlike a hash's hex digits.

Taken from https://github.com/can1357/oh-my-pi.
Precisely: https://raw.githubusercontent.com/can1357/oh-my-pi/85003ca/packages/coding-agent/src/hashline/bigrams.json")

(defun hl-hash (line)
  (elt hl-bigrams (% (sxhash line) 647)))

(defun hl-file-lines (file &optional beg end)
  "Return FILE contents as a list of strings.
With optional BEG and END (inclusive, 1-based), return the lines between that range."
  (with-temp-buffer
    (insert-file-contents-literally file)
    (let ((lines (string-lines (buffer-string))))
      (if beg
	  (cl-subseq lines (1- beg) end)
	lines))))

(defun hl-format-lines (lines &optional start include-content?)
  "Format LINES in hashline format.
START is 1-based (default 1).
If INCLUDE-CONTENT is non-nil, append `|LINE' after each hash."
  (string-join
   (cl-mapcar (lambda (line i)
		(if include-content?
		    (format "%d%2s|%s" i (hl-hash line) line)
		  (format "%d%2s" i (hl-hash line))))
	      lines
	      (number-sequence (or start 1) (+ (or start 1) (1- (length lines)))))
   "\n"))

(defun hl-file-read (file)
  "Return FILE contents in hashline format."
  (hl-format-lines (hl-file-lines file) nil t))

(defun hl-file-read-range (file beg end)
  "Return FILE contents in hashline format from lines BEG to END."
  (hl-format-lines (hl-file-lines file beg end) beg t))

;; FIXME might be redundant with =hl-file-line-hash= if I'm only
;; verifying the hash of the anchors and telling LLM to re-read the
;; file when they don't match
(defun hl-file-read-hashes (file)
  "Return FILE contents in hashline format without content."
  (hl-format-lines (hl-file-lines file)))

(defun hl-file-line-hash (file n)
  "Return the hash of the Nth line in FILE."
  (let ((lines (hl-file-lines file)))
      (hl-hash (elt lines (1- n)))))