//! API client
//!
//! `session` is so named since it manages resources and exposes `encapsulate`
//! and `open` API functionality to the consumer for a single API session
//! pertaining to a single domain. For a single domain, `Session` can and
//! should be a long-lived object managed by the consumer, since it leverages
//! various caches to improve performance.

pub mod api_helper;
mod chained_reader;
mod domain_cache;
#[doc(hidden)]
pub mod hook_processor;
#[doc(hidden)] // public for integration tests
pub mod http_client;
#[doc(hidden)]
pub mod policy_engine;
mod read_cache;
#[doc(hidden)]
pub mod reader;
mod seal_cache;
pub mod session;
pub mod version;
mod write_cache;

use crate::capsule::common::*;
use crate::session::session::SessionError;
use antimatter_api::apis::configuration;
use antimatter_api::apis::internal_api::{self as api};
use antimatter_api::models::*;
use anyhow::Result;
use std::collections::HashMap;
use std::hash::Hash;
use tokio::time::Duration;

lazy_static::lazy_static! {
    /// RUNTIME is a statically-scoped async runtime intended for internal
    /// use only. When internal functions need to use an async function,
    /// they should do so within a RUNTIME.block_on closure.
    #[doc(hidden)]
    pub static ref RUNTIME: tokio::runtime::Runtime = tokio::runtime::Builder::new_multi_thread().enable_all().thread_keep_alive(Duration::from_secs(900)).build().unwrap();
}

// #version
const API_TARGET_VERSION: &str = "v2";
const ELIDED_THRESHOLD: usize = 10;
const API_TIMEOUT: Duration = Duration::from_secs(30);

/// DataHookInvoker is responsible for sending the argument input to the
/// backend for data classification. This trait exists to make it possible
/// to mock interactions with the backend.
#[doc(hidden)]
pub trait DataHookInvoker: std::marker::Send + std::marker::Sync {
    /// invoke_hook should send the argument input for classification
    /// under the argument write context, using the argument hook name,
    /// within the argument domain.
    fn invoke_hook(
        &self,
        configuration: &configuration::Configuration,
        domain_id: &str,
        write_context_name: Option<&str>,
        hook_name: &str,
        data_tagging_hook_input: DataTaggingHookInput,
    ) -> Result<DataTaggingHookResponse, SessionError>;
}

/// DataTagger is the default implementation of DataHookInvoker that is used
/// when actually submitting data to the backend for classification.
#[doc(hidden)]
pub struct DataTagger;

impl DataHookInvoker for DataTagger {
    fn invoke_hook(
        &self,
        configuration: &configuration::Configuration,
        domain_id: &str,
        write_context_name: Option<&str>,
        hook_name: &str,
        data_tagging_hook_input: DataTaggingHookInput,
    ) -> Result<DataTaggingHookResponse, SessionError> {
        RUNTIME
            .block_on(api::domain_data_tagging_hook_invoke(
                configuration,
                domain_id,
                hook_name,
                data_tagging_hook_input,
                write_context_name,
            ))
            .map_err(|e| SessionError::APIError(format!("failed to invoke hook: {:?}", e)))
    }
}

/// Translates span indices from character-based (rune) positions to byte
/// positions within a UTF-8 string.
///
/// This function is designed to work with a UTF-8 encoded string
/// represented as `Vec<u8>`. It takes this vector along with a mutable
/// vector of `SpanTag`, which includes character-based start and end
/// indices (spans).
///
/// The function converts these spans from character-based indices to
/// byte-based indices, as per UTF-8 encoding. The operations are performed
/// in place to minimize memory allocation overheads.
///
/// # Arguments
/// * `data` - A `&Vec<u8>` representing the UTF-8 encoded string.
/// * `span_tags` - A `&mut Vec<SpanTag>` containing span tags with
///                 character-based indices.
fn spans_to_byte_idx(data: &[u8], span_tags: &mut Vec<SpanTag>) -> Result<(), SessionError> {
    let mut rune_to_byte_idx_map: HashMap<usize, usize> = HashMap::new();

    // Convert our data bytes to a UTF-8 string.
    let s = std::str::from_utf8(data)
        .map_err(|e| SessionError::Error(format!("failed to convert to UTF-8: {:?}", e)))?;

    // Collect all rune indexes.
    for span_tag in &mut *span_tags {
        rune_to_byte_idx_map.insert(span_tag.start, usize::MAX);
        rune_to_byte_idx_map.insert(span_tag.end, usize::MAX);
        // TODO: record max so we can stop counting bytesearly.
    }

    // Now we can count runes and bytes, updating our map as we go. This allows single pass.
    let mut ridx: usize = 0;
    let mut bidx: usize = 0;
    for r in s.chars() {
        if let Some(_val) = rune_to_byte_idx_map.get(&ridx) {
            rune_to_byte_idx_map.insert(ridx, bidx);
        }
        ridx += 1;
        bidx += r.len_utf8();
    }
    if let Some(_val) = rune_to_byte_idx_map.get(&ridx) {
        rune_to_byte_idx_map.insert(ridx, bidx);
    }

    // Update all the span tags.
    for span_tag in &mut *span_tags {
        if let Some(bidx) = rune_to_byte_idx_map.get(&span_tag.start) {
            if *bidx == usize::MAX {
                return Err(SessionError::Error(
                    "span tag rune byte index not processed".to_string(),
                ));
            }
            span_tag.start = *bidx;
        } else {
            return Err(SessionError::Error(
                "span tag rune byte index not found".to_string(),
            ));
        }

        if let Some(bidx) = rune_to_byte_idx_map.get(&span_tag.end) {
            if *bidx == usize::MAX {
                return Err(SessionError::Error(
                    "span tag rune byte index not processed".to_string(),
                ));
            }
            span_tag.end = *bidx;
        } else {
            return Err(SessionError::Error(
                "span tag rune byte index not found".to_string(),
            ));
        }
    }

    Ok(())
}

/// Processes a list of `SpanTag` objects, categorizing them into unique
/// and elided tags.
///
/// This function takes `SpanTag` objects, each with a name, type, value,
/// source, and hook version. It categorizes these tags based on their names
/// and unique attributes. Tags exceeding a predefined threshold
/// (ELIDED_THRESHOLD) are categorized as 'elided', others as 'unique'.
///
/// # Arguments
///
/// * `tags` - A vector of `SpanTag` objects to be processed.
///
/// # Returns
///
/// A tuple containing two vectors:
/// 1. `Vec<TagSummaryUniqueTagsInner>`: Unique tags under the
///    ELIDED_THRESHOLD, each with tag details and occurrence count.
/// 2. `Vec<TagSummaryElidedTagsInner>`: Elided tags with equal or more
///    unique configurations than ELIDED_THRESHOLD, each with tag name,
///    unique configurations count, and total occurrences.
#[doc(hidden)]
pub fn process_tags_to_unique_elided(
    tags: Vec<SpanTag>,
) -> (
    Vec<TagSummaryUniqueTagsInner>,
    Vec<TagSummaryElidedTagsInner>,
) {
    // SubTag represents the components of a tag that we will use to determine if it should be
    // represented as a unique set or a summary.
    #[derive(Eq, Hash, PartialEq, PartialOrd)]
    struct SubTag {
        value: String,
        tag_type: TagType,
        source: String,
        hook_version: (i32, i32, i32),
    }

    // parse the list of SpanTags into a map to be processed. If the element already exists in the
    // map, replace it. We consider the tag name to be unique
    let mut tag_map: HashMap<String, HashMap<SubTag, i32>> = HashMap::new();
    for tag in tags {
        let sub_tag = tag_map.entry(tag.tag.name.clone()).or_default();
        let entry = sub_tag
            .entry(SubTag {
                value: tag.tag.value.clone(),
                tag_type: tag.tag.tag_type.clone(),
                source: tag.tag.source.clone(),
                hook_version: tag.tag.hook_version,
            })
            .or_insert_with(|| 0);
        *entry += 1i32;
    }

    // process the map into a unique and elided tags
    let mut unique_tags: Vec<TagSummaryUniqueTagsInner> = Vec::new();
    let mut elided_tags: Vec<TagSummaryElidedTagsInner> = Vec::new();

    for (tag_name, tag_name_group) in tag_map.into_iter() {
        if tag_name_group.len() >= ELIDED_THRESHOLD {
            // ok we need a summary instead of a unique grouping
            elided_tags.push(TagSummaryElidedTagsInner {
                tag_name,
                num_unique_tags: tag_name_group.len() as i32,
                total_occurrences: tag_name_group.values().copied().sum::<i32>(),
            });
        } else {
            for (sub_tag, sub_tag_count) in tag_name_group.into_iter() {
                unique_tags.push(TagSummaryUniqueTagsInner {
                    tag: Box::new(Tag {
                        name: tag_name.clone(),
                        value: sub_tag.value.clone(),
                        r#type: TagTypeField::from(sub_tag.tag_type.clone()),
                        source: sub_tag.source.clone(),
                        hook_version: Some(format!(
                            "{}.{}.{}",
                            sub_tag.hook_version.0, sub_tag.hook_version.1, sub_tag.hook_version.2
                        )),
                    }),
                    occurrences: sub_tag_count,
                });
            }
        }
    }

    (unique_tags, elided_tags)
}

pub fn convert_to_option_vec(map: &HashMap<String, String>) -> Option<Vec<ReadParameter>> {
    // Convert HashMap entries to a Vec of ReadParameter
    let parameters: Vec<ReadParameter> = map
        .into_iter()
        .map(|(key, value)| ReadParameter {
            key: key.to_string(),
            value: value.to_string(),
        })
        .collect();

    // Return Some if the Vec is not empty, otherwise None
    if parameters.is_empty() {
        None
    } else {
        Some(parameters)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::capsule::common::{CapsuleTag, SpanTag, TagType};

    pub struct MockHookInvoker;

    impl DataHookInvoker for MockHookInvoker {
        // this mock implementation, will simply create the same tag for every data element it is
        // supplied.
        fn invoke_hook(
            &self,
            _configuration: &configuration::Configuration,
            _domain_id: &str,
            _write_context_name: Option<&str>,
            _hook_name: &str,
            data_tagging_hook_input: DataTaggingHookInput,
        ) -> Result<DataTaggingHookResponse, SessionError> {
            let mut response: DataTaggingHookResponse = DataTaggingHookResponse {
                version: "".to_string(),
                records: vec![],
            };
            for record in data_tagging_hook_input.records {
                let mut output_record: DataTaggingHookResponseRecordsInner =
                    DataTaggingHookResponseRecordsInner { elements: vec![] };
                for _ in record.elements {
                    output_record.elements.push(TagSet {
                        capsule_tags: vec![],
                        span_tags: vec![TagSetSpanTagsInner {
                            start: 0,
                            end: 5,
                            tags: vec![Tag {
                                name: "hook_name1".to_string(),
                                value: "hook_value1".to_string(),
                                r#type: Default::default(),
                                source: "hook_source1".to_string(),
                                hook_version: Some("1.2.3".to_string()),
                            }],
                        }],
                    })
                }
                response.records.push(output_record);
            }
            Ok(response)
        }
    }

    #[test]
    fn test_process_tags_to_unique_elided() {
        // Setup the test data
        let mut test_tags: Vec<SpanTag> = Vec::new();
        for i in 0..20 {
            let tag_name = if i < 10 {
                "common_tag".to_string()
            } else {
                format!("unique_tag_{}", i)
            };
            test_tags.push(SpanTag {
                tag: CapsuleTag {
                    name: tag_name,
                    tag_type: TagType::Str,
                    value: format!("value_{}", i),
                    source: "test_source".to_string(),
                    hook_version: (1, 0, i),
                },
                start: i as usize,
                end: (i + 1) as usize,
            });
        }

        let (unique_tags, elided_tags) = process_tags_to_unique_elided(test_tags);

        // Expecting 10 unique tags and 1 elided tag
        assert_eq!(unique_tags.len(), 10);
        assert_eq!(elided_tags.len(), 1);
    }

    #[test]
    fn test_rune_to_byte_index_conversion() {
        let mut sp_tgs: Vec<SpanTag> = vec![
            SpanTag {
                tag: CapsuleTag {
                    // More than 2 span tags to merge.
                    name: "name1".to_string(),
                    tag_type: TagType::Unary,
                    value: "value1".to_string(),
                    source: "source1".to_string(),
                    hook_version: (1, 2, 3),
                },
                start: 1,
                end: 5,
            },
            SpanTag {
                tag: CapsuleTag {
                    name: "name2".to_string(),
                    tag_type: TagType::Unary,
                    value: "value2".to_string(),
                    source: "source2".to_string(),
                    hook_version: (2, 3, 4),
                },
                start: 5,
                end: 15,
            },
        ];

        let example_string = "He🌍llo, 🌍! and something else.".as_bytes().to_vec();
        spans_to_byte_idx(&example_string, &mut sp_tgs).expect("test failure");

        assert_eq!(
            sp_tgs,
            vec![
                SpanTag {
                    tag: CapsuleTag {
                        // More than 2 span tags to merge.
                        name: "name1".to_string(),
                        tag_type: TagType::Unary,
                        value: "value1".to_string(),
                        source: "source1".to_string(),
                        hook_version: (1, 2, 3),
                    },
                    start: 1,
                    end: 8,
                },
                SpanTag {
                    tag: CapsuleTag {
                        name: "name2".to_string(),
                        tag_type: TagType::Unary,
                        value: "value2".to_string(),
                        source: "source2".to_string(),
                        hook_version: (2, 3, 4),
                    },
                    start: 8,
                    end: 21,
                },
            ]
        );
    }
}