import os
from typing import Optional, List, Dict, Tuple, Union

import pandas as pd

from pyhealth.data import Event, Visit, Patient
from pyhealth.datasets import BaseEHRDataset
from pyhealth.datasets.utils import strptime

# TODO: add other tables


class MIMIC3Dataset(BaseEHRDataset):
    """Base dataset for MIMIC-III dataset.

    The MIMIC-III dataset is a large dataset of de-identified health records of ICU
    patients. The dataset is available at https://mimic.physionet.org/.

    The basic information is stored in the following tables:
        - PATIENTS: defines a patient in the database, SUBJECT_ID.
        - ADMISSIONS: defines a patient's hospital admission, HADM_ID.

    We further support the following tables:
        - DIAGNOSES_ICD: contains ICD-9 diagnoses (ICD9CM code) for patients.
        - PROCEDURES_ICD: contains ICD-9 procedures (ICD9PROC code) for patients.
        - PRESCRIPTIONS: contains medication related order entries (NDC code)
            for patients.
        - LABEVENTS: contains laboratory measurements (MIMIC3_ITEMID code)
            for patients

    Args:
        dataset_name: name of the dataset.
        root: root directory of the raw data (should contain many csv files).
        tables: list of tables to be loaded (e.g., ["DIAGNOSES_ICD", "PROCEDURES_ICD"]).
        code_mapping: a dictionary containing the code mapping information.
            The key is a str of the source code vocabulary and the value is of
            two formats:
                (1) a str of the target code vocabulary;
                (2) a tuple with two elements. The first element is a str of the
                    target code vocabulary and the second element is a dict with
                    keys "source_kwargs" or "target_kwargs" and values of the
                    corresponding kwargs for the `CrossMap.map()` method.
            Default is empty dict, which means the original code will be used.
        dev: whether to enable dev mode (only use a small subset of the data).
            Default is False.
        refresh_cache: whether to refresh the cache; if true, the dataset will
            be processed from scratch and the cache will be updated. Default is False.

    Attributes:
        task: Optional[str], name of the task (e.g., "mortality prediction").
            Default is None.
        samples: Optional[List[Dict]], a list of samples, each sample is a dict with
            patient_id, visit_id, and other task-specific attributes as key.
            Default is None.
        patient_to_index: Optional[Dict[str, List[int]]], a dict mapping patient_id to
            a list of sample indices. Default is None.
        visit_to_index: Optional[Dict[str, List[int]]], a dict mapping visit_id to a
            list of sample indices. Default is None.

    Examples:
        >>> from pyhealth.datasets import MIMIC3Dataset
        >>> dataset = MIMIC3Dataset(
        ...         root="/srv/local/data/physionet.org/files/mimiciii/1.4",
        ...         tables=["DIAGNOSES_ICD", "PRESCRIPTIONS"],
        ...         code_mapping={"NDC": ("ATC", {"target_kwargs": {"level": 3}})},
        ...     )
        >>> dataset.stat()
        >>> dataset.info()
    """

    def parse_basic_info(self, patients: Dict[str, Patient]) -> Dict[str, Patient]:
        """Helper function which parses PATIENTS and ADMISSIONS tables.

        Will be called in `self.parse_tables()`

        Docs:
            - PATIENTS: https://mimic.mit.edu/docs/iii/tables/patients/
            - ADMISSIONS: https://mimic.mit.edu/docs/iii/tables/admissions/

        Args:
            patients: a dict of `Patient` objects indexed by patient_id which is updated with the mimic-3 table result.

        Returns:
            The updated patients dict.
        """
        # read patients table
        patients_df = pd.read_csv(
            os.path.join(self.root, "PATIENTS.csv"),
            dtype={"SUBJECT_ID": str},
            nrows=1000 if self.dev else None,
        )
        # read admissions table
        admissions_df = pd.read_csv(
            os.path.join(self.root, "ADMISSIONS.csv"),
            dtype={"SUBJECT_ID": str, "HADM_ID": str},
        )
        # merge patient and admission tables
        df = pd.merge(patients_df, admissions_df, on="SUBJECT_ID", how="inner")
        # sort by admission and discharge time
        df = df.sort_values(["SUBJECT_ID", "ADMITTIME", "DISCHTIME"], ascending=True)
        # group by patient
        df_group = df.groupby("SUBJECT_ID")

        # parallel unit of basic information (per patient)
        def basic_unit(p_id, p_info):
            patient = Patient(
                patient_id=p_id,
                birth_datetime=strptime(p_info["DOB"].values[0]),
                death_datetime=strptime(p_info["DOD_HOSP"].values[0]),
                gender=p_info["GENDER"].values[0],
                ethnicity=p_info["ETHNICITY"].values[0],
            )
            # load visits
            for v_id, v_info in p_info.groupby("HADM_ID"):
                visit = Visit(
                    visit_id=v_id,
                    patient_id=p_id,
                    encounter_time=strptime(v_info["ADMITTIME"].values[0]),
                    discharge_time=strptime(v_info["DISCHTIME"].values[0]),
                    discharge_status=v_info["HOSPITAL_EXPIRE_FLAG"].values[0],
                )
                # add visit
                patient.add_visit(visit)
            return patient

        # parallel apply
        df_group = df_group.parallel_apply(
            lambda x: basic_unit(x.SUBJECT_ID.unique()[0], x)
        )
        # summarize the results
        for pat_id, pat in df_group.items():
            patients[pat_id] = pat

        return patients

    def parse_diagnoses_icd(self, patients: Dict[str, Patient]) -> Dict[str, Patient]:
        """Helper function which parses DIAGNOSES_ICD table.

        Will be called in `self.parse_tables()`

        Docs:
            - DIAGNOSES_ICD: https://mimic.mit.edu/docs/iii/tables/diagnoses_icd/

        Args:
            patients: a dict of `Patient` objects indexed by patient_id.

        Returns:
            The updated patients dict.

        Note:
            MIMIC-III does not provide specific timestamps in DIAGNOSES_ICD
                table, so we set it to None.
        """
        table = "DIAGNOSES_ICD"
        # read table
        df = pd.read_csv(
            os.path.join(self.root, f"{table}.csv"),
            dtype={"SUBJECT_ID": str, "HADM_ID": str, "ICD9_CODE": str},
        )
        # drop records of the other patients
        df = df[df["SUBJECT_ID"].isin(patients.keys())]
        # drop rows with missing values
        df = df.dropna(subset=["SUBJECT_ID", "HADM_ID", "ICD9_CODE"])
        # sort by sequence number (i.e., priority)
        df = df.sort_values(["SUBJECT_ID", "HADM_ID", "SEQ_NUM"], ascending=True)
        # group by patient and visit
        group_df = df.groupby("SUBJECT_ID")

        # parallel unit of diagnosis (per patient)
        def diagnosis_unit(p_id, p_info):
            events = []
            for v_id, v_info in p_info.groupby("HADM_ID"):
                for code in v_info["ICD9_CODE"]:
                    event = Event(
                        code=code,
                        table=table,
                        vocabulary="ICD9CM",
                        visit_id=v_id,
                        patient_id=p_id,
                    )
                    events.append(event)
            return events

        # parallel apply
        group_df = group_df.parallel_apply(
            lambda x: diagnosis_unit(x.SUBJECT_ID.unique()[0], x)
        )

        # summarize the results
        patients = self._add_events_to_patient_dict(patients, group_df)
        return patients

    def parse_procedures_icd(self, patients: Dict[str, Patient]) -> Dict[str, Patient]:
        """Helper function which parses PROCEDURES_ICD table.

        Will be called in `self.parse_tables()`

        Docs:
            - PROCEDURES_ICD: https://mimic.mit.edu/docs/iii/tables/procedures_icd/

        Args:
            patients: a dict of `Patient` objects indexed by patient_id.

        Returns:
            The updated patients dict.

        Note:
            MIMIC-III does not provide specific timestamps in PROCEDURES_ICD
                table, so we set it to None.
        """
        table = "PROCEDURES_ICD"
        # read table
        df = pd.read_csv(
            os.path.join(self.root, f"{table}.csv"),
            dtype={"SUBJECT_ID": str, "HADM_ID": str, "ICD9_CODE": str},
        )
        # drop records of the other patients
        df = df[df["SUBJECT_ID"].isin(patients.keys())]
        # drop rows with missing values
        df = df.dropna(subset=["SUBJECT_ID", "HADM_ID", "SEQ_NUM", "ICD9_CODE"])
        # sort by sequence number (i.e., priority)
        df = df.sort_values(["SUBJECT_ID", "HADM_ID", "SEQ_NUM"], ascending=True)
        # group by patient and visit
        group_df = df.groupby("SUBJECT_ID")

        # parallel unit of procedure (per patient)
        def procedure_unit(p_id, p_info):
            events = []
            for v_id, v_info in p_info.groupby("HADM_ID"):
                for code in v_info["ICD9_CODE"]:
                    event = Event(
                        code=code,
                        table=table,
                        vocabulary="ICD9PROC",
                        visit_id=v_id,
                        patient_id=p_id,
                    )
                    events.append(event)
            return events

        # parallel apply
        group_df = group_df.parallel_apply(
            lambda x: procedure_unit(x.SUBJECT_ID.unique()[0], x)
        )

        # summarize the results
        patients = self._add_events_to_patient_dict(patients, group_df)
        return patients

    def parse_prescriptions(self, patients: Dict[str, Patient]) -> Dict[str, Patient]:
        """Helper function which parses PRESCRIPTIONS table.

        Will be called in `self.parse_tables()`

        Docs:
            - PRESCRIPTIONS: https://mimic.mit.edu/docs/iii/tables/prescriptions/

        Args:
            patients: a dict of `Patient` objects indexed by patient_id.

        Returns:
            The updated patients dict.
        """
        table = "PRESCRIPTIONS"
        # read table
        df = pd.read_csv(
            os.path.join(self.root, f"{table}.csv"),
            low_memory=False,
            dtype={"SUBJECT_ID": str, "HADM_ID": str, "NDC": str},
        )
        # drop records of the other patients
        df = df[df["SUBJECT_ID"].isin(patients.keys())]
        # drop rows with missing values
        df = df.dropna(subset=["SUBJECT_ID", "HADM_ID", "NDC"])
        # sort by start date and end date
        df = df.sort_values(
            ["SUBJECT_ID", "HADM_ID", "STARTDATE", "ENDDATE"], ascending=True
        )
        # group by patient and visit
        group_df = df.groupby("SUBJECT_ID")

        # parallel unit for prescription (per patient)
        def prescription_unit(p_id, p_info):
            events = []
            for v_id, v_info in p_info.groupby("HADM_ID"):
                for timestamp, code in zip(v_info["STARTDATE"], v_info["NDC"]):
                    event = Event(
                        code=code,
                        table=table,
                        vocabulary="NDC",
                        visit_id=v_id,
                        patient_id=p_id,
                        timestamp=strptime(timestamp),
                    )
                    events.append(event)
            return events

        # parallel apply
        group_df = group_df.parallel_apply(
            lambda x: prescription_unit(x.SUBJECT_ID.unique()[0], x)
        )

        # summarize the results
        patients = self._add_events_to_patient_dict(patients, group_df)
        return patients

    def parse_labevents(self, patients: Dict[str, Patient]) -> Dict[str, Patient]:
        """Helper function which parses LABEVENTS table.

        Will be called in `self.parse_tables()`

        Docs:
            - LABEVENTS: https://mimic.mit.edu/docs/iii/tables/labevents/

        Args:
            patients: a dict of `Patient` objects indexed by patient_id.

        Returns:
            The updated patients dict.
        """
        table = "LABEVENTS"
        # read table
        df = pd.read_csv(
            os.path.join(self.root, f"{table}.csv"),
            dtype={"SUBJECT_ID": str, "HADM_ID": str, "ITEMID": str},
        )
        # drop records of the other patients
        df = df[df["SUBJECT_ID"].isin(patients.keys())]
        # drop rows with missing values
        df = df.dropna(subset=["SUBJECT_ID", "HADM_ID", "ITEMID"])
        # sort by charttime
        df = df.sort_values(["SUBJECT_ID", "HADM_ID", "CHARTTIME"], ascending=True)
        # group by patient and visit
        group_df = df.groupby("SUBJECT_ID")

        # parallel unit for lab (per patient)
        def lab_unit(p_id, p_info):
            events = []
            for v_id, v_info in p_info.groupby("HADM_ID"):
                for timestamp, code in zip(v_info["CHARTTIME"], v_info["ITEMID"]):
                    event = Event(
                        code=code,
                        table=table,
                        vocabulary="MIMIC3_ITEMID",
                        visit_id=v_id,
                        patient_id=p_id,
                        timestamp=strptime(timestamp),
                    )
                    events.append(event)
            return events

        # parallel apply
        group_df = group_df.parallel_apply(
            lambda x: lab_unit(x.SUBJECT_ID.unique()[0], x)
        )

        # summarize the results
        patients = self._add_events_to_patient_dict(patients, group_df)
        return patients


if __name__ == "__main__":
    dataset = MIMIC3Dataset(
        root="https://storage.googleapis.com/pyhealth/mimiciii-demo/1.4/",
        tables=[
            "DIAGNOSES_ICD",
            "PROCEDURES_ICD",
            "PRESCRIPTIONS",
            "LABEVENTS",
        ],
        code_mapping={"NDC": "ATC"},
        dev=True,
        refresh_cache=True,
    )
    dataset.stat()
    dataset.info()

    # dataset = MIMIC3Dataset(
    #     root="/srv/local/data/physionet.org/files/mimiciii/1.4",
    #     tables=["DIAGNOSES_ICD", "PRESCRIPTIONS"],
    #     dev=True,
    #     code_mapping={"NDC": ("ATC", {"target_kwargs": {"level": 3}})},
    #     refresh_cache=False,
    # )
    # print(dataset.stat())
    # print(dataset.available_tables)
    # print(list(dataset.patients.values())[4])
