mod extractor;
mod hits;
mod resolver;
pub(super) mod syntax;

use crate::analyzer::usages::common::{language_for_file, language_for_target};
use crate::analyzer::usages::model::FuzzyResult;
use crate::analyzer::usages::outcome::{GraphFailureReason, GraphUsageOutcome};
use crate::analyzer::usages::scala_graph::extractor::scan_file;
use crate::analyzer::usages::scala_graph::resolver::{TargetSpec, resolve_scala_analyzer};
use crate::analyzer::usages::traits::UsageAnalyzer;
use crate::analyzer::{CodeUnit, IAnalyzer, Language, ProjectFile};
use crate::hash::HashSet;
use std::collections::BTreeSet;

#[derive(Default)]
pub struct ScalaUsageGraphStrategy {
    _private: (),
}

impl ScalaUsageGraphStrategy {
    pub fn new() -> Self {
        Self { _private: () }
    }

    pub fn can_handle(target: &CodeUnit) -> bool {
        language_for_target(target) == Language::Scala
    }

    pub(crate) fn find_graph_usages(
        &self,
        analyzer: &dyn IAnalyzer,
        overloads: &[CodeUnit],
        candidate_files: &HashSet<ProjectFile>,
        max_usages: usize,
    ) -> GraphUsageOutcome {
        if overloads.is_empty() {
            return GraphUsageOutcome::Resolved(FuzzyResult::empty_success());
        }

        let target = &overloads[0];
        if language_for_target(target) != Language::Scala {
            return GraphUsageOutcome::fallback_safe(
                target.fq_name(),
                GraphFailureReason::UnsupportedTargetLanguage("target is not Scala"),
                "ScalaUsageGraphStrategy",
            );
        }

        let Some(scala) = resolve_scala_analyzer(analyzer) else {
            return GraphUsageOutcome::fallback_safe(
                target.fq_name(),
                GraphFailureReason::MissingAnalyzerCapability(
                    "analyzer does not expose ScalaAnalyzer",
                ),
                "ScalaUsageGraphStrategy",
            );
        };

        let Some(spec) = TargetSpec::from_target(scala, target) else {
            return GraphUsageOutcome::fallback_safe(
                target.fq_name(),
                GraphFailureReason::UnsupportedTargetShape("target shape is unsupported"),
                "ScalaUsageGraphStrategy",
            );
        };

        let files: HashSet<ProjectFile> = candidate_files
            .iter()
            .filter(|file| language_for_file(file) == Language::Scala)
            .cloned()
            .chain(std::iter::once(target.source().clone()))
            .collect();

        let mut hits = BTreeSet::new();
        let mut limit_exceeded = false;
        for file in files {
            scan_file(
                scala,
                analyzer,
                &file,
                &spec,
                &mut hits,
                max_usages,
                &mut limit_exceeded,
            );
            if hits.len() > max_usages {
                return GraphUsageOutcome::Resolved(FuzzyResult::TooManyCallsites {
                    short_name: target.short_name().to_string(),
                    total_callsites: hits.len(),
                    limit: max_usages,
                });
            }
            if limit_exceeded {
                break;
            }
        }

        GraphUsageOutcome::Resolved(FuzzyResult::success(target.clone(), hits))
    }
}

impl UsageAnalyzer for ScalaUsageGraphStrategy {
    fn find_usages(
        &self,
        analyzer: &dyn IAnalyzer,
        overloads: &[CodeUnit],
        candidate_files: &HashSet<ProjectFile>,
        max_usages: usize,
    ) -> FuzzyResult {
        self.find_graph_usages(analyzer, overloads, candidate_files, max_usages)
            .into_fuzzy_result()
    }
}
