// Copyright 2023 Greptime Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::sync::Arc;

use ahash::HashSet;
use chrono::{DateTime, NaiveDateTime};
use chrono_tz::Tz;
use lazy_static::lazy_static;
use snafu::{OptionExt, ResultExt};

use crate::etl::error::{
    DateFailedToGetLocalTimezoneSnafu, DateFailedToGetTimestampSnafu, DateInvalidFormatSnafu,
    DateParseSnafu, DateParseTimezoneSnafu, EpochInvalidResolutionSnafu, Error,
    KeyMustBeStringSnafu, ProcessorFailedToParseStringSnafu, ProcessorMissingFieldSnafu,
    ProcessorUnsupportedValueSnafu, Result,
};
use crate::etl::field::{Fields, OneInputOneOutputField};
use crate::etl::processor::{
    yaml_bool, yaml_new_field, yaml_new_fields, yaml_string, yaml_strings, Processor,
    ProcessorBuilder, ProcessorKind, FIELDS_NAME, FIELD_NAME, IGNORE_MISSING_NAME,
};
use crate::etl::value::time::{
    MICROSECOND_RESOLUTION, MICRO_RESOLUTION, MILLISECOND_RESOLUTION, MILLI_RESOLUTION,
    MS_RESOLUTION, NANOSECOND_RESOLUTION, NANO_RESOLUTION, NS_RESOLUTION, SECOND_RESOLUTION,
    SEC_RESOLUTION, S_RESOLUTION, US_RESOLUTION,
};
use crate::etl::value::{Timestamp, Value};

pub(crate) const PROCESSOR_TIMESTAMP: &str = "timestamp";
const RESOLUTION_NAME: &str = "resolution";
const FORMATS_NAME: &str = "formats"; // default RFC3339

lazy_static! {
    static ref DEFAULT_FORMATS: Vec<(Arc<String>,Tz)> = vec![
                    // timezone with colon
                    "%Y-%m-%dT%H:%M:%S%:z",
                    "%Y-%m-%dT%H:%M:%S%.3f%:z",
                    "%Y-%m-%dT%H:%M:%S%.6f%:z",
                    "%Y-%m-%dT%H:%M:%S%.9f%:z",
                    // timezone without colon
                    "%Y-%m-%dT%H:%M:%S%z",
                    "%Y-%m-%dT%H:%M:%S%.3f%z",
                    "%Y-%m-%dT%H:%M:%S%.6f%z",
                    "%Y-%m-%dT%H:%M:%S%.9f%z",
                    // without timezone
                    "%Y-%m-%dT%H:%M:%SZ",
                    "%Y-%m-%dT%H:%M:%S",
                    "%Y-%m-%dT%H:%M:%S%.3f",
                    "%Y-%m-%dT%H:%M:%S%.6f",
                    "%Y-%m-%dT%H:%M:%S%.9f",
                ]
                .iter()
                .map(|s| (Arc::new(s.to_string()),Tz::UCT))
                .collect();
}

#[derive(Debug, Default)]
enum Resolution {
    Second,
    #[default]
    Milli,
    Micro,
    Nano,
}

impl TryFrom<&str> for Resolution {
    type Error = Error;

    fn try_from(s: &str) -> Result<Self> {
        match s {
            SECOND_RESOLUTION | SEC_RESOLUTION | S_RESOLUTION => Ok(Resolution::Second),
            MILLISECOND_RESOLUTION | MILLI_RESOLUTION | MS_RESOLUTION => Ok(Resolution::Milli),
            MICROSECOND_RESOLUTION | MICRO_RESOLUTION | US_RESOLUTION => Ok(Resolution::Micro),
            NANOSECOND_RESOLUTION | NANO_RESOLUTION | NS_RESOLUTION => Ok(Resolution::Nano),
            _ => EpochInvalidResolutionSnafu { resolution: s }.fail(),
        }
    }
}

#[derive(Debug)]
struct Formats(Vec<(Arc<String>, Tz)>);

impl Formats {
    fn new(mut formats: Vec<(Arc<String>, Tz)>) -> Self {
        formats.sort_by_key(|(key, _)| key.clone());
        formats.dedup();
        Formats(formats)
    }
}

impl Default for Formats {
    fn default() -> Self {
        Formats(DEFAULT_FORMATS.clone())
    }
}

impl std::ops::Deref for Formats {
    type Target = Vec<(Arc<String>, Tz)>;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

#[derive(Debug)]
pub struct TimestampProcessorBuilder {
    fields: Fields,
    formats: Formats,
    resolution: Resolution,
    ignore_missing: bool,
}

impl ProcessorBuilder for TimestampProcessorBuilder {
    fn output_keys(&self) -> HashSet<&str> {
        self.fields
            .iter()
            .map(|f| f.target_or_input_field())
            .collect()
    }

    fn input_keys(&self) -> HashSet<&str> {
        self.fields.iter().map(|f| f.input_field()).collect()
    }

    fn build(self, intermediate_keys: &[String]) -> Result<ProcessorKind> {
        self.build(intermediate_keys).map(ProcessorKind::Timestamp)
    }
}

impl TimestampProcessorBuilder {
    pub fn build(self, intermediate_keys: &[String]) -> Result<TimestampProcessor> {
        let mut real_fields = vec![];
        for field in self.fields.into_iter() {
            let input = OneInputOneOutputField::build(
                "timestamp",
                intermediate_keys,
                field.input_field(),
                field.target_or_input_field(),
            )?;
            real_fields.push(input);
        }
        Ok(TimestampProcessor {
            fields: real_fields,
            formats: self.formats,
            resolution: self.resolution,
            ignore_missing: self.ignore_missing,
        })
    }
}

/// support string, integer, float, time, epoch
#[derive(Debug, Default)]
pub struct TimestampProcessor {
    fields: Vec<OneInputOneOutputField>,
    formats: Formats,
    resolution: Resolution,
    ignore_missing: bool,
    // description
    // if
    // ignore_failure
    // on_failure
    // tag
}

impl TimestampProcessor {
    /// try to parse val with timezone first, if failed, parse without timezone
    fn try_parse(val: &str, fmt: &str, tz: Tz) -> Result<i64> {
        if let Ok(dt) = DateTime::parse_from_str(val, fmt) {
            Ok(dt
                .timestamp_nanos_opt()
                .context(DateFailedToGetTimestampSnafu)?)
        } else {
            let dt = NaiveDateTime::parse_from_str(val, fmt)
                .context(DateParseSnafu { value: val })?
                .and_local_timezone(tz)
                .single()
                .context(DateFailedToGetLocalTimezoneSnafu)?;
            Ok(dt
                .timestamp_nanos_opt()
                .context(DateFailedToGetTimestampSnafu)?)
        }
    }

    fn parse_time_str(&self, val: &str) -> Result<i64> {
        for (fmt, tz) in self.formats.iter() {
            if let Ok(ns) = Self::try_parse(val, fmt, *tz) {
                return Ok(ns);
            }
        }
        ProcessorFailedToParseStringSnafu {
            kind: PROCESSOR_TIMESTAMP,
            value: val.to_string(),
        }
        .fail()
    }

    fn parse(&self, val: &Value) -> Result<Timestamp> {
        let t: i64 = match val {
            Value::String(s) => {
                let t = s.parse::<i64>();
                match t {
                    Ok(t) => t,
                    Err(_) => {
                        let ns = self.parse_time_str(s)?;
                        return Ok(Timestamp::Nanosecond(ns));
                    }
                }
            }
            Value::Int16(i) => *i as i64,
            Value::Int32(i) => *i as i64,
            Value::Int64(i) => *i,
            Value::Uint8(i) => *i as i64,
            Value::Uint16(i) => *i as i64,
            Value::Uint32(i) => *i as i64,
            Value::Uint64(i) => *i as i64,
            Value::Float32(f) => *f as i64,
            Value::Float64(f) => *f as i64,

            Value::Timestamp(e) => match self.resolution {
                Resolution::Second => e.timestamp(),
                Resolution::Milli => e.timestamp_millis(),
                Resolution::Micro => e.timestamp_micros(),
                Resolution::Nano => e.timestamp_nanos(),
            },

            _ => {
                return ProcessorUnsupportedValueSnafu {
                    processor: PROCESSOR_TIMESTAMP,
                    val: val.to_string(),
                }
                .fail();
            }
        };

        match self.resolution {
            Resolution::Second => Ok(Timestamp::Second(t)),
            Resolution::Milli => Ok(Timestamp::Millisecond(t)),
            Resolution::Micro => Ok(Timestamp::Microsecond(t)),
            Resolution::Nano => Ok(Timestamp::Nanosecond(t)),
        }
    }
}

fn parse_formats(yaml: &yaml_rust::yaml::Yaml) -> Result<Vec<(Arc<String>, Tz)>> {
    return match yaml.as_vec() {
        Some(formats_yaml) => {
            let mut formats = Vec::with_capacity(formats_yaml.len());
            for v in formats_yaml {
                let s = yaml_strings(v, FORMATS_NAME)
                    .or(yaml_string(v, FORMATS_NAME).map(|s| vec![s]))?;
                if s.len() != 1 && s.len() != 2 {
                    return DateInvalidFormatSnafu {
                        processor: PROCESSOR_TIMESTAMP,
                        s: format!("{s:?}"),
                    }
                    .fail();
                }
                let mut iter = s.into_iter();
                // safety: unwrap is safe here
                let formatter = iter.next().unwrap();
                let tz = iter
                    .next()
                    .map(|tz| {
                        tz.parse::<Tz>()
                            .context(DateParseTimezoneSnafu { value: tz })
                    })
                    .unwrap_or(Ok(Tz::UTC))?;
                formats.push((Arc::new(formatter), tz));
            }
            Ok(formats)
        }
        None => DateInvalidFormatSnafu {
            processor: PROCESSOR_TIMESTAMP,
            s: format!("{yaml:?}"),
        }
        .fail(),
    };
}

impl TryFrom<&yaml_rust::yaml::Hash> for TimestampProcessorBuilder {
    type Error = Error;

    fn try_from(hash: &yaml_rust::yaml::Hash) -> Result<Self> {
        let mut fields = Fields::default();
        let mut formats = Formats::default();
        let mut resolution = Resolution::default();
        let mut ignore_missing = false;

        for (k, v) in hash {
            let key = k
                .as_str()
                .with_context(|| KeyMustBeStringSnafu { k: k.clone() })?;

            match key {
                FIELD_NAME => {
                    fields = Fields::one(yaml_new_field(v, FIELD_NAME)?);
                }
                FIELDS_NAME => {
                    fields = yaml_new_fields(v, FIELDS_NAME)?;
                }
                FORMATS_NAME => {
                    let formats_vec = parse_formats(v)?;
                    formats = Formats::new(formats_vec);
                }
                RESOLUTION_NAME => {
                    resolution = yaml_string(v, RESOLUTION_NAME)?.as_str().try_into()?;
                }
                IGNORE_MISSING_NAME => {
                    ignore_missing = yaml_bool(v, IGNORE_MISSING_NAME)?;
                }
                _ => {}
            }
        }

        let processor_builder = TimestampProcessorBuilder {
            fields,
            formats,
            resolution,
            ignore_missing,
        };

        Ok(processor_builder)
    }
}

impl Processor for TimestampProcessor {
    fn kind(&self) -> &str {
        PROCESSOR_TIMESTAMP
    }

    fn ignore_missing(&self) -> bool {
        self.ignore_missing
    }

    fn exec_mut(&self, val: &mut Vec<Value>) -> Result<()> {
        for field in self.fields.iter() {
            let index = field.input().index;
            match val.get(index) {
                Some(Value::Null) | None => {
                    if !self.ignore_missing {
                        return ProcessorMissingFieldSnafu {
                            processor: self.kind(),
                            field: field.input_name(),
                        }
                        .fail();
                    }
                }
                Some(v) => {
                    let result = self.parse(v)?;
                    let (_, index) = field.output();
                    val[*index] = Value::Timestamp(result);
                }
            }
        }
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use yaml_rust::YamlLoader;

    use super::{TimestampProcessor, TimestampProcessorBuilder};
    use crate::etl::value::{Timestamp, Value};

    fn builder_to_native_processor(builder: TimestampProcessorBuilder) -> TimestampProcessor {
        TimestampProcessor {
            fields: vec![],
            formats: builder.formats,
            resolution: builder.resolution,
            ignore_missing: builder.ignore_missing,
        }
    }

    #[test]
    fn test_parse_epoch() {
        let processor_yaml_str = r#"fields:
  - hello
resolution: s
formats:
  - "%Y-%m-%dT%H:%M:%S%:z"
  - "%Y-%m-%dT%H:%M:%S%.3f%:z"
  - "%Y-%m-%dT%H:%M:%S"
  - "%Y-%m-%dT%H:%M:%SZ"
"#;
        let yaml = &YamlLoader::load_from_str(processor_yaml_str).unwrap()[0];
        let timestamp_yaml = yaml.as_hash().unwrap();
        let processor = builder_to_native_processor(
            TimestampProcessorBuilder::try_from(timestamp_yaml).unwrap(),
        );

        let values = [
            (
                Value::String("1573840000".into()),
                Timestamp::Second(1573840000),
            ),
            (Value::Int32(1573840001), Timestamp::Second(1573840001)),
            (Value::Uint64(1573840002), Timestamp::Second(1573840002)),
            // float32 has a problem expressing the timestamp.
            // 1573840003.0_f32 as i64 is 1573840000
            //(Value::Float32(1573840003.0), Epoch::Second(1573840003)),
            (
                Value::String("2019-11-15T17:46:40Z".into()),
                Timestamp::Nanosecond(1573840000000000000),
            ),
        ];

        for (value, result) in values {
            let parsed = processor.parse(&value).unwrap();
            assert_eq!(parsed, result);
        }
        let values: Vec<&str> = vec![
            "2014-5-17T12:34:56",
            "2014-5-17T12:34:56Z",
            "2014-5-17T12:34:56+09:30",
            "2014-5-17T12:34:56.000+09:30",
            "2014-5-17T12:34:56-0930",
            "2014-5-17T12:34:56.000-0930",
        ]
        .into_iter()
        .collect();

        for value in values {
            let parsed = processor.parse(&Value::String(value.into()));
            assert!(parsed.is_ok());
        }
    }

    #[test]
    fn test_parse_with_timezone() {
        let processor_yaml_str = r#"fields:
  - hello
resolution: s
formats:
  - ["%Y-%m-%dT%H:%M:%S%:z", "Asia/Tokyo"]
  - ["%Y-%m-%dT%H:%M:%S%.3f%:z", "Asia/Tokyo"]
  - ["%Y-%m-%dT%H:%M:%S", "Asia/Tokyo"]
  - ["%Y-%m-%dT%H:%M:%SZ", "Asia/Tokyo"]
"#;
        let yaml = &YamlLoader::load_from_str(processor_yaml_str).unwrap()[0];
        let timestamp_yaml = yaml.as_hash().unwrap();
        let processor = builder_to_native_processor(
            TimestampProcessorBuilder::try_from(timestamp_yaml).unwrap(),
        );

        let values: Vec<&str> = vec![
            "2014-5-17T12:34:56",
            "2014-5-17T12:34:56Z",
            "2014-5-17T12:34:56+09:30",
            "2014-5-17T12:34:56.000+09:30",
            "2014-5-17T12:34:56-0930",
            "2014-5-17T12:34:56.000-0930",
        ]
        .into_iter()
        .collect();

        for value in values {
            let parsed = processor.parse(&Value::String(value.into()));
            assert!(parsed.is_ok());
        }
    }
}