variable-core 0.1.4

#![allow(unused_assignments)]

use std::collections::{HashMap, HashSet};

use miette::{Diagnostic, SourceSpan};
use thiserror::Error;

use crate::ast::{VarFile, VarType};
use crate::lexer::Span;

#[derive(Error, Debug, Diagnostic)]
pub enum ValidationError {
    #[error("duplicate feature name: `{name}`")]
    DuplicateFeature {
        name: String,
        #[label("first defined here")]
        first: SourceSpan,
        #[label("duplicate defined here")]
        duplicate: SourceSpan,
    },

    #[error("duplicate feature id `{id}`")]
    DuplicateFeatureId {
        id: u32,
        #[label("first defined here")]
        first: SourceSpan,
        #[label("duplicate defined here")]
        duplicate: SourceSpan,
    },

    #[error("duplicate variable name `{name}` in feature `{feature}`")]
    DuplicateVariable {
        feature: String,
        name: String,
        #[label("first defined here")]
        first: SourceSpan,
        #[label("duplicate defined here")]
        duplicate: SourceSpan,
    },

    #[error("duplicate variable id `{id}` in feature `{feature}`")]
    DuplicateVariableId {
        feature: String,
        id: u32,
        #[label("first defined here")]
        first: SourceSpan,
        #[label("duplicate defined here")]
        duplicate: SourceSpan,
    },

    #[error("duplicate struct name: `{name}`")]
    DuplicateStruct {
        name: String,
        #[label("first defined here")]
        first: SourceSpan,
        #[label("duplicate defined here")]
        duplicate: SourceSpan,
    },

    #[error("duplicate struct id `{id}`")]
    DuplicateStructId {
        id: u32,
        #[label("first defined here")]
        first: SourceSpan,
        #[label("duplicate defined here")]
        duplicate: SourceSpan,
    },

    #[error("duplicate field name `{name}` in struct `{struct_name}`")]
    DuplicateField {
        struct_name: String,
        name: String,
        #[label("first defined here")]
        first: SourceSpan,
        #[label("duplicate defined here")]
        duplicate: SourceSpan,
    },

    #[error("duplicate field id `{id}` in struct `{struct_name}`")]
    DuplicateFieldId {
        struct_name: String,
        id: u32,
        #[label("first defined here")]
        first: SourceSpan,
        #[label("duplicate defined here")]
        duplicate: SourceSpan,
    },

    #[error("unknown struct type `{type_name}` for variable `{variable}` in feature `{feature}`")]
    UnknownStructType {
        feature: String,
        variable: String,
        type_name: String,
        #[label("used here")]
        span: SourceSpan,
    },

    #[error("unknown field `{field}` in struct literal for type `{struct_name}`")]
    UnknownStructField {
        struct_name: String,
        field: String,
        #[label("used here")]
        span: SourceSpan,
    },
}

fn span_to_source_span(span: &Span) -> SourceSpan {
    SourceSpan::from(span.offset)
}

pub fn validate(var_file: &VarFile) -> Result<(), Vec<ValidationError>> {
    let mut errors = Vec::new();

    // Collect known struct names for type reference validation
    let mut struct_names_set: HashSet<&str> = HashSet::new();

    // Check for duplicate struct names and IDs
    let mut struct_names: HashMap<&str, &Span> = HashMap::new();
    let mut struct_ids: HashMap<u32, &Span> = HashMap::new();
    for struct_def in &var_file.structs {
        struct_names_set.insert(&struct_def.name);

        if let Some(first_span) = struct_names.get(struct_def.name.as_str()) {
            errors.push(ValidationError::DuplicateStruct {
                name: struct_def.name.clone(),
                first: span_to_source_span(first_span),
                duplicate: span_to_source_span(&struct_def.span),
            });
        } else {
            struct_names.insert(&struct_def.name, &struct_def.span);
        }

        if let Some(first_span) = struct_ids.get(&struct_def.id) {
            errors.push(ValidationError::DuplicateStructId {
                id: struct_def.id,
                first: span_to_source_span(first_span),
                duplicate: span_to_source_span(&struct_def.span),
            });
        } else {
            struct_ids.insert(struct_def.id, &struct_def.span);
        }

        // Check for duplicate field names and IDs within struct
        let mut field_names: HashMap<&str, &Span> = HashMap::new();
        let mut field_ids: HashMap<u32, &Span> = HashMap::new();
        for field in &struct_def.fields {
            if let Some(first_span) = field_names.get(field.name.as_str()) {
                errors.push(ValidationError::DuplicateField {
                    struct_name: struct_def.name.clone(),
                    name: field.name.clone(),
                    first: span_to_source_span(first_span),
                    duplicate: span_to_source_span(&field.span),
                });
            } else {
                field_names.insert(&field.name, &field.span);
            }

            if let Some(first_span) = field_ids.get(&field.id) {
                errors.push(ValidationError::DuplicateFieldId {
                    struct_name: struct_def.name.clone(),
                    id: field.id,
                    first: span_to_source_span(first_span),
                    duplicate: span_to_source_span(&field.span),
                });
            } else {
                field_ids.insert(field.id, &field.span);
            }
        }
    }

    // Build a map of struct field names for literal validation
    let struct_field_names: HashMap<&str, HashSet<&str>> = var_file
        .structs
        .iter()
        .map(|s| {
            let fields: HashSet<&str> = s.fields.iter().map(|f| f.name.as_str()).collect();
            (s.name.as_str(), fields)
        })
        .collect();

    // Check for duplicate feature names and IDs
    let mut feature_names: HashMap<&str, &Span> = HashMap::new();
    let mut feature_ids: HashMap<u32, &Span> = HashMap::new();
    for feature in &var_file.features {
        if let Some(first_span) = feature_names.get(feature.name.as_str()) {
            errors.push(ValidationError::DuplicateFeature {
                name: feature.name.clone(),
                first: span_to_source_span(first_span),
                duplicate: span_to_source_span(&feature.span),
            });
        } else {
            feature_names.insert(&feature.name, &feature.span);
        }

        if let Some(first_span) = feature_ids.get(&feature.id) {
            errors.push(ValidationError::DuplicateFeatureId {
                id: feature.id,
                first: span_to_source_span(first_span),
                duplicate: span_to_source_span(&feature.span),
            });
        } else {
            feature_ids.insert(feature.id, &feature.span);
        }
    }

    // Check for duplicate variable names and IDs within each feature,
    // and validate struct type references
    for feature in &var_file.features {
        let mut var_names: HashMap<&str, &Span> = HashMap::new();
        let mut var_ids: HashMap<u32, &Span> = HashMap::new();
        for variable in &feature.variables {
            if let Some(first_span) = var_names.get(variable.name.as_str()) {
                errors.push(ValidationError::DuplicateVariable {
                    feature: feature.name.clone(),
                    name: variable.name.clone(),
                    first: span_to_source_span(first_span),
                    duplicate: span_to_source_span(&variable.span),
                });
            } else {
                var_names.insert(&variable.name, &variable.span);
            }

            if let Some(first_span) = var_ids.get(&variable.id) {
                errors.push(ValidationError::DuplicateVariableId {
                    feature: feature.name.clone(),
                    id: variable.id,
                    first: span_to_source_span(first_span),
                    duplicate: span_to_source_span(&variable.span),
                });
            } else {
                var_ids.insert(variable.id, &variable.span);
            }

            // Validate struct type references resolve to a defined struct
            if let VarType::Struct(ref struct_name) = variable.var_type {
                if !struct_names_set.contains(struct_name.as_str()) {
                    errors.push(ValidationError::UnknownStructType {
                        feature: feature.name.clone(),
                        variable: variable.name.clone(),
                        type_name: struct_name.clone(),
                        span: span_to_source_span(&variable.span),
                    });
                }

                // Validate struct literal fields exist in the struct definition
                if let crate::ast::Value::Struct { fields, .. } = &variable.default {
                    if let Some(valid_fields) = struct_field_names.get(struct_name.as_str()) {
                        for field_name in fields.keys() {
                            if !valid_fields.contains(field_name.as_str()) {
                                errors.push(ValidationError::UnknownStructField {
                                    struct_name: struct_name.clone(),
                                    field: field_name.clone(),
                                    span: span_to_source_span(&variable.span),
                                });
                            }
                        }
                    }
                }
            }
        }
    }

    if errors.is_empty() {
        Ok(())
    } else {
        Err(errors)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::lexer::lex;
    use crate::parser::parse;

    fn parse_and_validate(input: &str) -> Result<VarFile, Vec<ValidationError>> {
        let tokens = lex(input).expect("lex failed");
        let var_file = parse(tokens).expect("parse failed");
        validate(&var_file)?;
        Ok(var_file)
    }

    #[test]
    fn valid_file_passes() {
        let input = r#"1: Feature Checkout = {
    1: enabled Boolean = true
    2: max_items Integer = 50
}

2: Feature Search = {
    1: query String = "default"
}"#;
        assert!(parse_and_validate(input).is_ok());
    }

    #[test]
    fn duplicate_feature_name_error() {
        let input = r#"1: Feature Checkout = {
    1: enabled Boolean = true
}

2: Feature Checkout = {
    1: max_items Integer = 50
}"#;
        let err = parse_and_validate(input).unwrap_err();
        assert_eq!(err.len(), 1);
        match &err[0] {
            ValidationError::DuplicateFeature { name, .. } => {
                assert_eq!(name, "Checkout");
            }
            _ => panic!("expected DuplicateFeature error"),
        }
    }

    #[test]
    fn duplicate_variable_name_error() {
        let input = r#"1: Feature Checkout = {
    1: enabled Boolean = true
    2: enabled Boolean = false
}"#;
        let err = parse_and_validate(input).unwrap_err();
        assert_eq!(err.len(), 1);
        match &err[0] {
            ValidationError::DuplicateVariable { feature, name, .. } => {
                assert_eq!(feature, "Checkout");
                assert_eq!(name, "enabled");
            }
            _ => panic!("expected DuplicateVariable error"),
        }
    }

    #[test]
    fn error_has_correct_line_info() {
        let input = r#"1: Feature Checkout = {
    1: enabled Boolean = true
}

2: Feature Checkout = {
    1: max_items Integer = 50
}"#;
        let err = parse_and_validate(input).unwrap_err();
        match &err[0] {
            ValidationError::DuplicateFeature {
                first, duplicate, ..
            } => {
                // First "Feature" is at offset 0
                assert_eq!(first.offset(), 0);
                // Duplicate "Feature" is on line 5
                assert!(duplicate.offset() > 0);
            }
            _ => panic!("expected DuplicateFeature error"),
        }
    }

    #[test]
    fn duplicate_feature_id_error() {
        let input = r#"1: Feature Checkout = {
    1: enabled Boolean = true
}

1: Feature Search = {
    1: query String = "default"
}"#;
        let err = parse_and_validate(input).unwrap_err();
        assert_eq!(err.len(), 1);
        match &err[0] {
            ValidationError::DuplicateFeatureId { id, .. } => {
                assert_eq!(*id, 1);
            }
            _ => panic!("expected DuplicateFeatureId error"),
        }
    }

    #[test]
    fn duplicate_variable_id_error() {
        let input = r#"1: Feature Checkout = {
    1: enabled Boolean = true
    1: max_items Integer = 50
}"#;
        let err = parse_and_validate(input).unwrap_err();
        assert_eq!(err.len(), 1);
        match &err[0] {
            ValidationError::DuplicateVariableId { feature, id, .. } => {
                assert_eq!(feature, "Checkout");
                assert_eq!(*id, 1);
            }
            _ => panic!("expected DuplicateVariableId error"),
        }
    }

    #[test]
    fn valid_file_with_struct_passes() {
        let input = r#"1: Struct Theme = {
    1: dark_mode Boolean = false
    2: font_size Integer = 14
}

1: Feature Dashboard = {
    1: enabled Boolean = true
    2: theme Theme = Theme {}
}"#;
        assert!(parse_and_validate(input).is_ok());
    }

    #[test]
    fn duplicate_struct_name_error() {
        let input = r#"1: Struct Theme = {
    1: dark_mode Boolean = false
}

2: Struct Theme = {
    1: font_size Integer = 14
}"#;
        let err = parse_and_validate(input).unwrap_err();
        assert_eq!(err.len(), 1);
        match &err[0] {
            ValidationError::DuplicateStruct { name, .. } => {
                assert_eq!(name, "Theme");
            }
            _ => panic!("expected DuplicateStruct error"),
        }
    }

    #[test]
    fn duplicate_struct_id_error() {
        let input = r#"1: Struct Theme = {
    1: dark_mode Boolean = false
}

1: Struct Config = {
    1: retries Integer = 3
}"#;
        let err = parse_and_validate(input).unwrap_err();
        assert_eq!(err.len(), 1);
        match &err[0] {
            ValidationError::DuplicateStructId { id, .. } => {
                assert_eq!(*id, 1);
            }
            _ => panic!("expected DuplicateStructId error"),
        }
    }

    #[test]
    fn duplicate_field_name_error() {
        let input = r#"1: Struct Theme = {
    1: dark_mode Boolean = false
    2: dark_mode Boolean = true
}"#;
        let err = parse_and_validate(input).unwrap_err();
        assert_eq!(err.len(), 1);
        match &err[0] {
            ValidationError::DuplicateField {
                struct_name, name, ..
            } => {
                assert_eq!(struct_name, "Theme");
                assert_eq!(name, "dark_mode");
            }
            _ => panic!("expected DuplicateField error"),
        }
    }

    #[test]
    fn duplicate_field_id_error() {
        let input = r#"1: Struct Theme = {
    1: dark_mode Boolean = false
    1: font_size Integer = 14
}"#;
        let err = parse_and_validate(input).unwrap_err();
        assert_eq!(err.len(), 1);
        match &err[0] {
            ValidationError::DuplicateFieldId {
                struct_name, id, ..
            } => {
                assert_eq!(struct_name, "Theme");
                assert_eq!(*id, 1);
            }
            _ => panic!("expected DuplicateFieldId error"),
        }
    }

    #[test]
    fn unknown_struct_type_error() {
        let input = r#"1: Feature Dashboard = {
    1: theme UnknownType = UnknownType {}
}"#;
        let err = parse_and_validate(input).unwrap_err();
        assert_eq!(err.len(), 1);
        match &err[0] {
            ValidationError::UnknownStructType {
                feature,
                variable,
                type_name,
                ..
            } => {
                assert_eq!(feature, "Dashboard");
                assert_eq!(variable, "theme");
                assert_eq!(type_name, "UnknownType");
            }
            _ => panic!("expected UnknownStructType error"),
        }
    }

    #[test]
    fn unknown_struct_field_in_literal_error() {
        let input = r#"1: Struct Theme = {
    1: dark_mode Boolean = false
}

1: Feature Dashboard = {
    1: theme Theme = Theme { nonexistent = true }
}"#;
        let err = parse_and_validate(input).unwrap_err();
        assert_eq!(err.len(), 1);
        match &err[0] {
            ValidationError::UnknownStructField {
                struct_name, field, ..
            } => {
                assert_eq!(struct_name, "Theme");
                assert_eq!(field, "nonexistent");
            }
            _ => panic!("expected UnknownStructField error"),
        }
    }
}