import os
import json
from collections import defaultdict
from pathlib import Path
import re


def match_tags_by_key(prob_tags, sol_tags, extract_key):
    prob_index = defaultdict(list)
    sol_index = defaultdict(list)

    for i, tag in enumerate(prob_tags):
        prob_index[extract_key(tag)].append(i)

    for i, tag in enumerate(sol_tags):
        sol_index[extract_key(tag)].append(i)

    index_pairs = []
    for num in prob_index:
        for i, j in zip(prob_index[num], sol_index[num]):
            index_pairs.append((i, j))

    return index_pairs


def solution_chapter_after_chapter_ends(chapter_starts, solution_starts, max_size):
    return solution_starts, chapter_starts[1:] + [max_size]


def solution_after_all_problem_ends(chapter_starts, solution_starts, max_size):
    return chapter_starts[1:] + [solution_starts[0]], solution_starts[1:] + [max_size]


def join_chapter_tags(
    text,
    chapter_tags,
    solution_tags,
    prob_re,
    extract_key,
    compute_ends=solution_chapter_after_chapter_ends,
):
    def segment(text, prob_tags, sol_tags, prob_end, sol_end):
        prob_pos = [tag.start() for tag in prob_tags] + [prob_end]
        sol_pos = [tag.start() for tag in sol_tags] + [sol_end]
        probs = [
            text[start:end].strip() for start, end in zip(prob_pos[:-1], prob_pos[1:])
        ]
        sols = [
            text[start:end].strip() for start, end in zip(sol_pos[:-1], sol_pos[1:])
        ]
        return probs, sols

    """
    for chapter_tag in chapter_tags:
        print(chapter_tag)
    for solution_tag in solution_tags:
        print(solution_tag)"""

    print(len(chapter_tags), len(solution_tags))
    if len(chapter_tags) != len(solution_tags):
        return []

    tags = list(prob_re.finditer(text))
    chapter_starts = [tag.start() for tag in chapter_tags]
    solution_starts = [tag.start() for tag in solution_tags]
    chapter_ends, solution_ends = compute_ends(
        chapter_starts, solution_starts, len(text)
    )

    prob_batch_tags, sol_batch_tags = [], []
    for start, end in zip(chapter_starts, chapter_ends):
        prob_batch_tags.append(
            [tag for tag in tags if tag.start() > start and tag.start() < end]
        )
    for start, end in zip(solution_starts, solution_ends):
        sol_batch_tags.append(
            [tag for tag in tags if tag.start() > start and tag.start() < end]
        )

    pairs = []
    for prob_tags, sol_tags, prob_end, sol_end in zip(
        prob_batch_tags, sol_batch_tags, chapter_ends, solution_ends
    ):
        """for tag in prob_tags:
            print(tag)
        for tag in sol_tags:
            print(tag)"""
        print(len(prob_tags), len(sol_tags))
        probs, sols = segment(text, prob_tags, sol_tags, prob_end, sol_end)
        pairs.extend(
            [
                (probs[i], sols[j], prob_tags[i], sol_tags[j])
                for i, j in match_tags_by_key(prob_tags, sol_tags, extract_key)
            ]
        )
    pairs.sort(key=lambda x: x[2].start())

    """for _, _, prob_tag, sol_tag in pairs:
        print(prob_tag, sol_tag)"""

    return pairs


def join_chapter(
    text,
    chapter_re,
    solution_re,
    prob_re,
    extract_key,
    compute_ends=solution_chapter_after_chapter_ends,
):
    chapter_tags = list(chapter_re.finditer(text))
    solution_tags = list(solution_re.finditer(text))
    return join_chapter_tags(
        text, chapter_tags, solution_tags, prob_re, extract_key, compute_ends
    )


def join_prob_sol(tags, text):
    prob = None
    prob_tag, sol_tag, prob_label = None, None, None
    pairs = []

    counter = 0
    while counter < len(tags):
        if tags[counter][1]:
            sol_tag = tags[counter][0]
            while counter < len(tags) and tags[counter][1]:
                counter += 1

            start = sol_tag.end()
            end = tags[counter][0].start() if counter < len(tags) else len(text)

            if prob:
                pairs.append((prob, text[start:end], prob_tag, sol_tag, prob_label))
        else:
            while counter < len(tags) and not tags[counter][1]:
                prob_tag = tags[counter][0]
                prob_label = tags[counter][0].group(1)
                start = prob_tag.end()
                end = (
                    tags[counter + 1][0].start()
                    if counter + 1 < len(tags)
                    else len(text)
                )
                prob = text[start:end]
                counter += 1

    return pairs


min_length = 5


project_root = Path(__file__).parent.parent.parent
problem_type_mapping = {
    "A": "Algebra",
    "C": "Combinatorics",
    "G": "Geometry",
    "N": "Number Theory"
    }

def write_pairs(filename, pairs):
    year = re.search(r"(\d{4})", str(filename)).group(1)
    with open(filename, "w", encoding="utf-8") as f:
        for problem, solution, prob_tag, sol_tag, prob_label in pairs:
            if (
                len(problem) > prob_tag.end() - prob_tag.start() + min_length
                and len(solution) > sol_tag.end() - sol_tag.start() + min_length
            ):
                resource_path = Path(filename).relative_to(project_root).as_posix()
                f.write(
                    json.dumps(
                        {
                            "year": year,
                            "tier": "T3",
                            "problem_label": prob_label,
                            "problem_type": problem_type_mapping.get(prob_label[0]),
                            "exam": "JBMO-SL" if "en-shortlist" in resource_path else "JBMO",
                            "problem": problem,
                            "solution": solution,
                            "metadata": {
                                "resource_path": resource_path,
                                "problem_match": prob_tag.group(0),
                                "solution_match": sol_tag.group(0),
                            },
                            
                        },
                        ensure_ascii=False,
                    )
                    + "\n"
                )


base = "../../ru-books"
seg_path = "."

dirname = "library"
path = os.path.join(base, dirname)