#!/usr/bin/env python3

"""
This script compiles HLG from

    - H, the ctc topology, built from phones contained in data/lang/lexicon.txt
    - L, the lexicon, built from data/lang/L_disambig.pt

        Caution: We use a lexicon that contains disambiguation symbols

    - G, the LM, built from data/lm/G_3_gram.fst.txt

The generated HLG is saved in data/lm/HLG.pt
"""
import k2
import torch

from icefall.lexicon import Lexicon


def main():
    lexicon = Lexicon("data/lang")
    max_token_id = max(lexicon.tokens)
    H = k2.ctc_topo(max_token_id)
    L = k2.Fsa.from_dict(torch.load("data/lang/L_disambig.pt"))
    with open("data/lm/G_3_gram.fst.txt") as f:
        G = k2.Fsa.from_openfst(f.read(), acceptor=False)

    first_token_disambig_id = lexicon.phones["#0"]
    first_word_disambig_id = lexicon.words["#0"]

    L = k2.arc_sort(L)
    G = k2.arc_sort(G)

    print("Intersecting L and G")
    LG = k2.compose(L, G)
    print(f"LG shape: {LG.shape}")

    print("Connecting LG")
    LG = k2.connect(LG)
    print(f"LG shape after k2.connect: {LG.shape}")

    print(type(LG.aux_labels))
    print("Determinizing LG")

    LG = k2.determinize(LG)
    print(type(LG.aux_labels))

    print("Connecting LG after k2.determinize")
    LG = k2.connect(LG)

    print("Removing disambiguation symbols on LG")

    LG.labels[LG.labels >= first_token_disambig_id] = 0

    assert isinstance(LG.aux_labels, k2.RaggedInt)
    LG.aux_labels.values()[LG.aux_labels.values() >= first_word_disambig_id] = 0

    LG = k2.remove_epsilon(LG)
    print(f"LG shape after k2.remove_epsilon: {LG.shape}")

    LG = k2.connect(LG)
    LG.aux_labels = k2.ragged.remove_values_eq(LG.aux_labels, 0)

    print("Arc sorting LG")
    LG = k2.arc_sort(LG)

    print("Composing H and LG")
    HLG = k2.compose(H, LG, inner_labels="phones")

    print("Connecting LG")
    HLG = k2.connect(HLG)

    print("Arc sorting LG")
    HLG = k2.arc_sort(HLG)

    print("Saving HLG.pt to data/lm")
    torch.save(HLG.as_dict(), "data/lm/HLG.pt")


if __name__ == "__main__":
    main()