use std::env;
use std::fs;
use std::path::Path;
use std::process;
use std::collections::HashMap;

fn main() {
    #[cfg(feature = "embed")]
    {
        minijinja_embed::embed_templates!("templates");
    }

    // Only run i18n validation in debug builds or when explicitly requested
    if env::var("CARGO_CFG_DEBUG_ASSERTIONS").is_ok() || env::var("VALIDATE_I18N").is_ok() {
        validate_i18n_files();
    }
}

fn validate_i18n_files() {
    let i18n_dir = Path::new("i18n");
    if !i18n_dir.exists() {
        return; // Skip if no i18n directory
    }

    println!("cargo:rerun-if-changed=i18n/");
    
    // Check for duplicate keys
    for entry in fs::read_dir(i18n_dir).unwrap() {
        let lang_dir = entry.unwrap().path();
        if lang_dir.is_dir() {
            if check_for_duplicates(&lang_dir) {
                eprintln!("❌ Build failed: Duplicate translation keys found!");
                process::exit(1);
            }
        }
    }

    // Check synchronization between en-us and fr-ca
    if check_synchronization() {
        eprintln!("❌ Build failed: Translation files are not synchronized!");
        process::exit(1);
    }

    println!("✅ i18n validation passed");
}

fn check_for_duplicates(dir: &Path) -> bool {
    let mut has_duplicates = false;
    
    for entry in fs::read_dir(dir).unwrap() {
        let file = entry.unwrap().path();
        if file.extension().and_then(|s| s.to_str()) == Some("ftl") {
            if let Ok(content) = fs::read_to_string(&file) {
                let mut seen_keys = HashMap::new();
                
                for (line_num, line) in content.lines().enumerate() {
                    if let Some(key) = parse_translation_key(line) {
                        if let Some(prev_line) = seen_keys.insert(key.clone(), line_num + 1) {
                            eprintln!(
                                "Duplicate key '{}' in {}: line {} and line {}",
                                key,
                                file.display(),
                                prev_line,
                                line_num + 1
                            );
                            has_duplicates = true;
                        }
                    }
                }
            }
        }
    }
    
    has_duplicates
}

fn check_synchronization() -> bool {
    let files = ["ui.ftl", "common.ftl", "actions.ftl", "errors.ftl", "forms.ftl"];
    let mut has_sync_issues = false;
    
    for file in files.iter() {
        let en_file = Path::new("i18n/en-us").join(file);
        let fr_file = Path::new("i18n/fr-ca").join(file);
        
        if en_file.exists() && fr_file.exists() {
            let en_count = count_translation_keys(&en_file);
            let fr_count = count_translation_keys(&fr_file);
            
            if en_count != fr_count {
                eprintln!(
                    "Key count mismatch in {}: EN={}, FR={}",
                    file, en_count, fr_count
                );
                has_sync_issues = true;
            }
        }
    }
    
    has_sync_issues
}

fn count_translation_keys(file: &Path) -> usize {
    if let Ok(content) = fs::read_to_string(file) {
        content
            .lines()
            .filter(|line| parse_translation_key(line).is_some())
            .count()
    } else {
        0
    }
}

fn parse_translation_key(line: &str) -> Option<String> {
    let trimmed = line.trim();
    
    // Skip comments and empty lines
    if trimmed.starts_with('#') || trimmed.is_empty() {
        return None;
    }
    
    // Look for pattern: key = value
    if let Some(eq_pos) = trimmed.find(" =") {
        let key = &trimmed[..eq_pos];
        // Validate key format: alphanumeric, hyphens, underscores only
        if key.chars().all(|c| c.is_alphanumeric() || c == '-' || c == '_') && !key.is_empty() {
            return Some(key.to_string());
        }
    }
    
    None
}