//! Driver for working with Redshift.

use lazy_static::lazy_static;
use regex::Regex;
use serde::Deserialize;
use std::{
    collections::HashMap,
    fmt,
    str::{self, FromStr},
};

use crate::common::*;
use crate::drivers::postgres::PostgresLocator;
use crate::drivers::{
    postgres_shared::{pg_quote, PgName},
    s3::S3Locator,
};

mod local_data;
mod write_local_data;
mod write_remote_data;

use local_data::local_data_helper;
use write_local_data::write_local_data_helper;
use write_remote_data::write_remote_data_helper;

/// A locator for a Redshift table.
#[derive(Debug, Clone)]
pub struct RedshiftLocator {
    /// Internally store this as a PostgreSQL locator.
    postgres_locator: PostgresLocator,
}

impl RedshiftLocator {
    /// The URL for this locator.
    pub(crate) fn url(&self) -> &UrlWithHiddenPassword {
        self.postgres_locator.url()
    }

    /// The table name for this locator.
    pub(crate) fn table_name(&self) -> &PgName {
        self.postgres_locator.table_name()
    }
}

impl fmt::Display for RedshiftLocator {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let pg = self.postgres_locator.to_string();
        assert!(pg.starts_with("postgres:"));
        pg.replacen("postgres:", "redshift:", 1).fmt(f)
    }
}

#[test]
fn do_not_display_password() {
    let l = "redshift://user:pass@host/db#table"
        .parse::<RedshiftLocator>()
        .expect("could not parse locator");
    assert_eq!(format!("{}", l), "redshift://user:XXXXXX@host/db#table");
}

impl FromStr for RedshiftLocator {
    type Err = Error;

    fn from_str(s: &str) -> Result<Self> {
        if !s.starts_with("redshift:") {
            // Don't print the unparsed locator in the error because that would
            // leak the password.
            return Err(format_err!("Redshift locator must begin with redshift://"));
        }
        let postgres_locator = s.replacen("redshift:", "postgres:", 1).parse()?;
        Ok(RedshiftLocator { postgres_locator })
    }
}

impl Locator for RedshiftLocator {
    fn as_any(&self) -> &dyn Any {
        self
    }

    fn schema(&self, ctx: Context) -> BoxFuture<Option<Schema>> {
        self.postgres_locator.schema(ctx)
    }

    fn local_data(
        &self,
        ctx: Context,
        shared_args: SharedArguments<Unverified>,
        source_args: SourceArguments<Unverified>,
    ) -> BoxFuture<Option<BoxStream<CsvStream>>> {
        local_data_helper(ctx, self.to_owned(), shared_args, source_args).boxed()
    }

    fn write_local_data(
        &self,
        ctx: Context,
        data: BoxStream<CsvStream>,
        shared_args: SharedArguments<Unverified>,
        dest_args: DestinationArguments<Unverified>,
    ) -> BoxFuture<BoxStream<BoxFuture<BoxLocator>>> {
        write_local_data_helper(ctx, self.to_owned(), data, shared_args, dest_args)
            .boxed()
    }

    fn supports_write_remote_data(&self, source: &dyn Locator) -> bool {
        // We can only do `write_remote_data` if `source` is a `S3Locator`.
        // Otherwise, we need to do `write_local_data` like normal.
        source.as_any().is::<S3Locator>()
    }

    fn write_remote_data(
        &self,
        ctx: Context,
        source: BoxLocator,
        shared_args: SharedArguments<Unverified>,
        source_args: SourceArguments<Unverified>,
        dest_args: DestinationArguments<Unverified>,
    ) -> BoxFuture<Vec<BoxLocator>> {
        write_remote_data_helper(
            ctx,
            source,
            self.to_owned(),
            shared_args,
            source_args,
            dest_args,
        )
        .boxed()
    }
}

impl LocatorStatic for RedshiftLocator {
    fn scheme() -> &'static str {
        "redshift:"
    }

    fn features() -> Features {
        Features {
            locator: LocatorFeatures::Schema
                | LocatorFeatures::LocalData
                | LocatorFeatures::WriteLocalData,
            write_schema_if_exists: EnumSet::empty(),
            source_args: SourceArgumentsFeatures::DriverArgs
                | SourceArgumentsFeatures::WhereClause,
            dest_args: DestinationArgumentsFeatures::DriverArgs.into(),
            dest_if_exists: IfExistsFeatures::Append
                | IfExistsFeatures::Error
                | IfExistsFeatures::Overwrite
                | IfExistsFeatures::Upsert,
            _placeholder: (),
        }
    }
}

/// Arguments passed to the RedShift driver.
#[derive(Debug, Deserialize)]
pub(crate) struct RedshiftDriverArguments {
    // Insert this as a "-- partner: " comment in generated queries. AWS uses
    // this to keep track of which tools generate which queries.
    partner: Option<String>,
    // Everything we don't recognize is treated as a credential, for backwards
    // compatibility.
    #[serde(flatten)]
    credentials: HashMap<String, String>,
}

impl RedshiftDriverArguments {
    /// Return a "-- partner: " SQL fragment if we need one, or "" if we don't.
    pub(crate) fn partner_sql(&self) -> Result<String> {
        match &self.partner {
            Some(partner) => {
                if partner.contains('\n') || partner.contains("--") {
                    Err(format_err!(
                        "unsupported characters in partner: {:?}",
                        partner
                    ))
                } else {
                    Ok(format!("-- partner: {}\n", partner))
                }
            }
            None => Ok("".to_owned()),
        }
    }

    /// Given a `DriverArgs` structure, convert it into Redshift credentials SQL.
    pub(crate) fn credentials_sql(&self) -> Result<String> {
        let mut out = vec![];
        for (k, v) in &self.credentials {
            lazy_static! {
                static ref KEY_RE: Regex = Regex::new("^[_A-Za-z0-9]+$")
                    .expect("invalid regex in source code");
            }
            if !KEY_RE.is_match(k) {
                return Err(format_err!("cannot pass {:?} as Redshift credential", k));
            }
            writeln!(&mut out, "{} {}", k, pg_quote(v))?;
        }
        Ok(String::from_utf8(out).expect("found non-UTF-8 SQL"))
    }
}