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use indexmap::map::IndexMap;
use itertools::Itertools;

use crate::{base, proto, Warnable};
use crate::base::{ArrayProperties, DataType, IndexKey, NodeProperties, SensitivitySpace, Value, ValueProperties};
use crate::components::{Component, Expandable, Mechanism, Sensitivity};
use crate::errors::*;
use crate::utilities::{get_literal, prepend, check_sensitivity_properties};
use crate::utilities::inference::infer_property;
use crate::utilities::privacy::privacy_usage_check;

impl Component for proto::ExponentialMechanism {
    fn propagate_property(
        &self,
        privacy_definition: &Option<proto::PrivacyDefinition>,
        _public_arguments: IndexMap<base::IndexKey, &Value>,
        properties: base::NodeProperties,
        node_id: u32,
    ) -> Result<Warnable<ValueProperties>> {
        let privacy_definition = privacy_definition.as_ref()
            .ok_or_else(|| "privacy_definition must be defined")?;

        if privacy_definition.group_size == 0 {
            return Err("group size must be greater than zero".into());
        }

        let utilities_property: ArrayProperties = properties
            .get(&IndexKey::from("utilities"))
            .ok_or("utilities: missing")?.array()
            .map_err(prepend("utilities:"))?.clone();

        if utilities_property.data_type != DataType::Float {
            return Err("utilities: data_type must be float".into());
        }

        let candidates_property: ArrayProperties = properties
            .get(&IndexKey::from("candidates"))
            .ok_or_else(|| Error::from("candidates: missing"))?.array()?.clone();

        if !candidates_property.releasable {
            return Err(Error::from("candidates: must be public"))
        }

        if utilities_property.num_records()? != candidates_property.num_records()? {
            return Err("utilities and candidates must share the same number of records".into());
        }
        if utilities_property.num_columns()? != candidates_property.num_columns()? {
            return Err("utilities and candidates must share the same number of columns".into());
        }

        if utilities_property.num_columns()? != 1 {
            return Err(Error::from("exponential mechanism only works with one column at a time"))
        }

        let aggregator = utilities_property.aggregator.clone()
            .ok_or_else(|| Error::from("aggregator: missing"))?;

        // sensitivity must be computable
        let sensitivity_values = aggregator.component.compute_sensitivity(
            privacy_definition,
            &aggregator.properties,
            &SensitivitySpace::Exponential)?;

        // make sure sensitivities are an f64 array
        sensitivity_values.array()?.float()?;

        let output_property = ArrayProperties {
            num_records: Some(1),
            num_columns: Some(1),
            nullity: false,
            releasable: true,
            c_stability: 1,
            aggregator: None,
            nature: None,
            data_type: candidates_property.data_type.clone(),
            dataset_id: None,
            node_id: node_id as i64,
            is_not_empty: true,
            dimensionality: Some(0),
            group_id: utilities_property.group_id,
            naturally_ordered: true,
            sample_proportion: None
        };

        let privacy_usage = self.privacy_usage.iter().cloned().map(Ok)
            .fold1(|l, r| l? + r?)
            .ok_or_else(|| "privacy_usage: must be defined")??;

        let warnings = privacy_usage_check(
            &privacy_usage,
            output_property.num_records,
            privacy_definition.strict_parameter_checks)?;

        Ok(Warnable(output_property.into(), warnings))
    }
}

impl Expandable for proto::ExponentialMechanism {
    fn expand_component(
        &self,
        privacy_definition: &Option<proto::PrivacyDefinition>,
        component: &proto::Component,
        _public_arguments: &IndexMap<IndexKey, &Value>,
        properties: &base::NodeProperties,
        component_id: u32,
        mut maximum_id: u32,
    ) -> Result<base::ComponentExpansion> {
        let mut expansion = base::ComponentExpansion::default();

        let utilities_property: ArrayProperties = properties.get::<IndexKey>(&"utilities".into())
            .ok_or("utilities: missing")?.array()
            .map_err(prepend("utilities:"))?.clone();

        let privacy_definition = privacy_definition.as_ref()
            .ok_or_else(|| "privacy definition must be defined")?;

        // noising
        let mut noise_component = component.clone();

        if self.privacy_usage.len() != 1 {
            return Err(Error::from("privacy usage must be of length one"));
        }

        // update the privacy usage
        if let Some(proto::component::Variant::ExponentialMechanism(variant)) = &mut noise_component.variant {
            variant.privacy_usage = vec![self.privacy_usage[0].actual_to_effective(
                utilities_property.sample_proportion.unwrap_or(1.),
                utilities_property.c_stability,
                privacy_definition.group_size)?];
            // this case should never happen
        } else { return Err(Error::from("Variant must be defined")) }

        if let Some(sensitivity_property) = properties.get(&IndexKey::from("sensitivity")) {
            if privacy_definition.protect_sensitivity {
                return Err(Error::from("custom sensitivities may only be passed if protect_sensitivity is disabled"))
            }
            check_sensitivity_properties(sensitivity_property.array()?, &utilities_property)?;
        } else {
            let aggregator = utilities_property.aggregator
                .ok_or_else(|| Error::from("aggregator: missing"))?;

            let sensitivity = aggregator.component.compute_sensitivity(
                privacy_definition,
                &aggregator.properties,
                &SensitivitySpace::Exponential)?;

            // exponential sensitivity cannot currently be modified by lipschitz constants

            maximum_id += 1;
            let id_sensitivity = maximum_id;
            let (patch_node, release) = get_literal(sensitivity, component.submission)?;
            expansion.computation_graph.insert(id_sensitivity, patch_node);
            expansion.properties.insert(id_sensitivity, infer_property(&release.value, None, id_sensitivity)?);
            expansion.releases.insert(id_sensitivity, release);
            noise_component.insert_argument(&"sensitivity".into(), id_sensitivity);
        }

        expansion.computation_graph.insert(component_id, noise_component);

        Ok(expansion)
    }
}

impl Mechanism for proto::ExponentialMechanism {
    fn get_privacy_usage(
        &self,
        privacy_definition: &proto::PrivacyDefinition,
        release_usage: Option<&Vec<proto::PrivacyUsage>>,
        properties: &NodeProperties,
    ) -> Result<Option<Vec<proto::PrivacyUsage>>> {
        let data_property = properties.get::<IndexKey>(&"data".into())
            .ok_or("data: missing")?.array()
            .map_err(prepend("data:"))?;

        Some(release_usage.unwrap_or_else(|| &self.privacy_usage).iter()
            .map(|usage| usage.effective_to_actual(
                data_property.sample_proportion.unwrap_or(1.),
                data_property.c_stability,
                privacy_definition.group_size))
            .collect::<Result<Vec<proto::PrivacyUsage>>>()).transpose()
    }
}