from __future__ import annotations

import typing as t

from sqlglot import exp, generator, parser, tokens
from sqlglot.dialects.dialect import Dialect, inline_array_sql, var_map_sql
from sqlglot.errors import ParseError
from sqlglot.parser import parse_var_map
from sqlglot.tokens import TokenType


def _lower_func(sql):
    index = sql.index("(")
    return sql[:index].lower() + sql[index:]


class ClickHouse(Dialect):
    normalize_functions = None
    null_ordering = "nulls_are_last"

    class Tokenizer(tokens.Tokenizer):
        COMMENTS = ["--", "#", "#!", ("/*", "*/")]
        IDENTIFIERS = ['"', "`"]

        KEYWORDS = {
            **tokens.Tokenizer.KEYWORDS,
            "ASOF": TokenType.ASOF,
            "GLOBAL": TokenType.GLOBAL,
            "DATETIME64": TokenType.DATETIME,
            "FINAL": TokenType.FINAL,
            "FLOAT32": TokenType.FLOAT,
            "FLOAT64": TokenType.DOUBLE,
            "INT16": TokenType.SMALLINT,
            "INT32": TokenType.INT,
            "INT64": TokenType.BIGINT,
            "INT8": TokenType.TINYINT,
            "TUPLE": TokenType.STRUCT,
        }

    class Parser(parser.Parser):
        FUNCTIONS = {
            **parser.Parser.FUNCTIONS,  # type: ignore
            "MAP": parse_var_map,
            "QUANTILE": lambda params, args: exp.Quantile(this=args, quantile=params),
            "QUANTILES": lambda params, args: exp.Quantiles(parameters=params, expressions=args),
            "QUANTILEIF": lambda params, args: exp.QuantileIf(parameters=params, expressions=args),
        }

        RANGE_PARSERS = {
            **parser.Parser.RANGE_PARSERS,
            TokenType.GLOBAL: lambda self, this: self._match(TokenType.IN)
            and self._parse_in(this, is_global=True),
        }

        JOIN_KINDS = {*parser.Parser.JOIN_KINDS, TokenType.ANY, TokenType.ASOF}  # type: ignore

        TABLE_ALIAS_TOKENS = {*parser.Parser.TABLE_ALIAS_TOKENS} - {TokenType.ANY}  # type: ignore

        def _parse_in(
            self, this: t.Optional[exp.Expression], is_global: bool = False
        ) -> exp.Expression:
            this = super()._parse_in(this)
            this.set("is_global", is_global)
            return this

        def _parse_table(
            self, schema: bool = False, alias_tokens: t.Optional[t.Collection[TokenType]] = None
        ) -> t.Optional[exp.Expression]:
            this = super()._parse_table(schema=schema, alias_tokens=alias_tokens)

            if self._match(TokenType.FINAL):
                this = self.expression(exp.Final, this=this)

            return this

        def _parse_position(self) -> exp.Expression:
            this = super()._parse_position()
            # clickhouse position args are swapped
            substr = this.this
            this.args["this"] = this.args.get("substr")
            this.args["substr"] = substr
            return this

        # https://clickhouse.com/docs/en/sql-reference/statements/select/with/
        def _parse_cte(self) -> exp.Expression:
            index = self._index
            try:
                # WITH <identifier> AS <subquery expression>
                return super()._parse_cte()
            except ParseError:
                # WITH <expression> AS <identifier>
                self._retreat(index)
                statement = self._parse_statement()

                if statement and isinstance(statement.this, exp.Alias):
                    self.raise_error("Expected CTE to have alias")

                return self.expression(exp.CTE, this=statement, alias=statement and statement.this)

    class Generator(generator.Generator):
        STRUCT_DELIMITER = ("(", ")")

        TYPE_MAPPING = {
            **generator.Generator.TYPE_MAPPING,  # type: ignore
            exp.DataType.Type.NULLABLE: "Nullable",
            exp.DataType.Type.DATETIME: "DateTime64",
            exp.DataType.Type.MAP: "Map",
            exp.DataType.Type.ARRAY: "Array",
            exp.DataType.Type.STRUCT: "Tuple",
            exp.DataType.Type.TINYINT: "Int8",
            exp.DataType.Type.SMALLINT: "Int16",
            exp.DataType.Type.INT: "Int32",
            exp.DataType.Type.BIGINT: "Int64",
            exp.DataType.Type.FLOAT: "Float32",
            exp.DataType.Type.DOUBLE: "Float64",
        }

        TRANSFORMS = {
            **generator.Generator.TRANSFORMS,  # type: ignore
            exp.Array: inline_array_sql,
            exp.StrPosition: lambda self, e: f"position({self.format_args(e.this, e.args.get('substr'), e.args.get('position'))})",
            exp.Final: lambda self, e: f"{self.sql(e, 'this')} FINAL",
            exp.Map: lambda self, e: _lower_func(var_map_sql(self, e)),
            exp.VarMap: lambda self, e: _lower_func(var_map_sql(self, e)),
            exp.Quantile: lambda self, e: f"quantile{self._param_args_sql(e, 'quantile', 'this')}",
            exp.Quantiles: lambda self, e: f"quantiles{self._param_args_sql(e, 'parameters', 'expressions')}",
            exp.QuantileIf: lambda self, e: f"quantileIf{self._param_args_sql(e, 'parameters', 'expressions')}",
        }

        EXPLICIT_UNION = True

        def _param_args_sql(
            self, expression: exp.Expression, params_name: str, args_name: str
        ) -> str:
            params = self.format_args(self.expressions(expression, params_name))
            args = self.format_args(self.expressions(expression, args_name))
            return f"({params})({args})"

        def cte_sql(self, expression: exp.CTE) -> str:
            if isinstance(expression.this, exp.Alias):
                return self.sql(expression, "this")

            return super().cte_sql(expression)