// 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 ahash::HashSet;

/// Protocol specific context
/// for carrying options(like HTTP header options) within the query context
#[derive(Debug, Clone, Default)]
pub enum ProtocolCtx {
    #[default]
    None,
    OtlpMetric(OtlpMetricCtx),
}

impl ProtocolCtx {
    pub fn get_otlp_metric_ctx(&self) -> Option<&OtlpMetricCtx> {
        match self {
            ProtocolCtx::None => None,
            ProtocolCtx::OtlpMetric(opt) => Some(opt),
        }
    }
}

/// The context information for OTLP metrics ingestion.
/// - `promote_all_resource_attrs`
///     If true, all resource attributes will be promoted to the final table schema.
/// - `resource_attrs`
///     If `promote_all_resource_attrs` is true, then the list is an exclude list from `ignore_resource_attrs`.
///     If `promote_all_resource_attrs` is false, then this list is a include list from `promote_resource_attrs`.
/// - `promote_scope_attrs`
///     If true, all scope attributes will be promoted to the final table schema.
///     Along with the scope name, scope version and scope schema URL.
/// - `with_metric_engine`
/// - `experimental_enable_exponential_histogram`
/// - `is_legacy`
///     If the user uses OTLP metrics ingestion before v0.16, it uses the old path.
///     So we call this path 'legacy'.
///     After v0.16, we store the OTLP metrics using prometheus compatible format, the new path.
///     The difference is how we convert the input data into the final table schema.
#[derive(Debug, Clone, Default)]
pub struct OtlpMetricCtx {
    pub promote_all_resource_attrs: bool,
    pub resource_attrs: HashSet<String>,
    pub promote_scope_attrs: bool,
    pub with_metric_engine: bool,
    pub experimental_enable_exponential_histogram: bool,
    pub is_legacy: bool,
    /// Set from the server's `otlp.experimental_enable_resource_info`; off
    /// means the resource descriptor is not synthesized at all.
    pub resource_info: bool,
    pub metric_type: MetricType,
    pub metric_translation_strategy: OtlpMetricTranslationStrategy,
}

impl OtlpMetricCtx {
    pub fn set_metric_type(&mut self, metric_type: MetricType) {
        self.metric_type = metric_type;
    }
}

#[derive(Debug, Clone, Default)]
pub enum MetricType {
    // default value when initializing the context
    #[default]
    Init,
    NonMonotonicSum,
    MonotonicSum,
    Gauge,
    Histogram,
    ExponentialHistogram,
    Summary,
}

#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
pub enum OtlpMetricTranslationStrategy {
    #[default]
    UnderscoreEscapingWithSuffixes,
    UnderscoreEscapingWithoutSuffixes,
    NoUtf8EscapingWithSuffixes,
    NoTranslation,
}

impl OtlpMetricTranslationStrategy {
    pub const VALUES: [&'static str; 4] = [
        "UnderscoreEscapingWithSuffixes",
        "UnderscoreEscapingWithoutSuffixes",
        "NoUTF8EscapingWithSuffixes",
        "NoTranslation",
    ];

    pub fn as_str(self) -> &'static str {
        match self {
            Self::UnderscoreEscapingWithSuffixes => "UnderscoreEscapingWithSuffixes",
            Self::UnderscoreEscapingWithoutSuffixes => "UnderscoreEscapingWithoutSuffixes",
            Self::NoUtf8EscapingWithSuffixes => "NoUTF8EscapingWithSuffixes",
            Self::NoTranslation => "NoTranslation",
        }
    }

    pub fn should_escape(self) -> bool {
        matches!(
            self,
            Self::UnderscoreEscapingWithSuffixes | Self::UnderscoreEscapingWithoutSuffixes
        )
    }

    pub fn should_add_suffixes(self) -> bool {
        matches!(
            self,
            Self::UnderscoreEscapingWithSuffixes | Self::NoUtf8EscapingWithSuffixes
        )
    }
}

impl std::str::FromStr for OtlpMetricTranslationStrategy {
    type Err = ();

    fn from_str(value: &str) -> Result<Self, Self::Err> {
        match value {
            "UnderscoreEscapingWithSuffixes" => Ok(Self::UnderscoreEscapingWithSuffixes),
            "UnderscoreEscapingWithoutSuffixes" => Ok(Self::UnderscoreEscapingWithoutSuffixes),
            "NoUTF8EscapingWithSuffixes" => Ok(Self::NoUtf8EscapingWithSuffixes),
            "NoTranslation" => Ok(Self::NoTranslation),
            _ => Err(()),
        }
    }
}

impl std::fmt::Display for OtlpMetricTranslationStrategy {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(self.as_str())
    }
}
