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"""Parse explain and extract parameters."""

from __future__ import annotations
from collections import deque, defaultdict
from typing import Mapping, Sequence, TypeVar, Callable
import bson.json_util as json
from workload_execution import QueryParameters
from config import AbtCalibratorConfig
from database_instance import DatabaseInstance
from cost_estimator import CostModelParameters, ExecutionStats
import execution_tree
import physical_tree

__all__ = ['extract_parameters', 'extract_execution_stats']


async def extract_parameters(
        config: AbtCalibratorConfig, database: DatabaseInstance,
        abt_types: Sequence[str]) -> Mapping[str, Sequence[CostModelParameters]]:
    """Read measurements from database and extract cost model parameters for the given ABT types."""

    stats = defaultdict(list)

    docs = await database.get_all_documents(config.input_collection_name)
    for result in docs:
        explain = json.loads(result['explain'])
        query_parameters = QueryParameters.from_json(result['query_parameters'])
        res = parse_explain(explain, abt_types)
        for abt_type, es in res.items():
            stats[abt_type] += [
                CostModelParameters(execution_stats=stat, query_params=query_parameters)
                for stat in es
            ]
        if config.trace and len(res) > 0:
            print(res)
    return stats


Node = TypeVar('Node')


def find_abt_node_by_type(root: physical_tree.Node, abt_type: str) -> Sequence[physical_tree.Node]:
    """Find ABT node by its type."""
    return find_nodes(root, lambda node: node.node_type == abt_type)


def find_nodes(root: Node, predicate: Callable[[Node], bool]) -> list[Node]:
    """Find nodes in the given tree which satisfy the predicate."""

    def impl(node: Node, predicate: Callable[[Node], bool], result: list[Node]) -> Node:
        if predicate(node):
            result.append(node)
        for child in node.children:
            impl(child, predicate, result)

    result: list[Node] = []
    impl(root, predicate, result)
    return result


def get_excution_stats(root: execution_tree.Node, node_id: int) -> ExecutionStats:
    """Extract execution stats from the given Execution Tree for the ABT node defined with the given node_id."""
    queue: deque[execution_tree.Node] = deque()
    queue.append(root)

    execution_time: int = 0
    n_returned: int = root.n_returned
    n_processed: int = 0

    n_sbe_nodes: int = 0

    while len(queue) > 0:
        size = len(queue)
        for _ in range(size):
            node = queue.popleft()
            if node.plan_node_id == node_id:
                execution_time += node.get_execution_time()
                n_processed = max(n_processed, node.n_processed)
                n_sbe_nodes += 1
            for child in node.children:
                queue.append(child)

    assert n_sbe_nodes <= 1

    return ExecutionStats(execution_time=execution_time, n_returned=n_returned,
                          n_processed=n_processed)


def parse_explain(explain: Mapping[str, any], abt_types: Sequence[str]):
    """Extract ExecutionStats from the given explain for the given ABT types."""

    try:
        et = execution_tree.build_execution_tree(explain['executionStats'])
        pt = physical_tree.build(explain['queryPlanner']['winningPlan']['optimizerPlan'])
    except Exception as exception:
        print(f'*** Failed to parse explain with the followinf error: {exception}')
        print(explain)
        raise exception

    return extract_execution_stats(et, pt, abt_types)


def extract_execution_stats(et: execution_tree.Node, pt: physical_tree.Node,
                            abt_types: Sequence[str]) -> Mapping[str, Sequence[ExecutionStats]]:
    """Extract ExecutionStats from the given SBE and ABT trees for the given ABT types."""

    if len(abt_types) == 0:
        abt_types = get_abt_types(pt)

    try:
        result: Mapping[str, ExecutionStats] = defaultdict(list)
        for abt_type in abt_types:
            for abt_node in find_abt_node_by_type(pt, abt_type):
                execution_stats = get_excution_stats(et, abt_node.plan_node_id)
                result[abt_type].append(execution_stats)
        return result
    except AssertionError as ae:
        print(f'{pt.node_type} {ae} {pt}')
        raise ae


def get_abt_types(pt: physical_tree.Node) -> Sequence[str]:
    """Extract types of all ABT nodes in the given ABT."""
    abt_types = set()
    queue: deque[physical_tree.Node] = deque()
    queue.append(pt)

    while len(queue) > 0:
        size = len(queue)
        for _ in range(size):
            node = queue.popleft()
            abt_types.add(node.node_type)
            for child in node.children:
                queue.append(child)
    return abt_types