//! Text normalization for TTS preprocessing
//!
//! This module provides text normalization capabilities including:
//! - Case normalization
//! - Punctuation removal
//! - Abbreviation expansion
//! - Number to word conversion
//! - Whitespace normalization

use crate::error::{Result, TtsError};
use regex::Regex;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use unicode_normalization::UnicodeNormalization;

/// Configuration for text normalization
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TextNormalizerConfig {
    /// Convert text to lowercase
    pub lowercase: bool,
    /// Remove punctuation marks
    pub remove_punctuation: bool,
    /// Expand abbreviations to full words
    pub expand_abbreviations: bool,
    /// Convert numbers to words
    pub normalize_numbers: bool,
    /// Normalize whitespace (collapse multiple spaces)
    pub normalize_whitespace: bool,
}

impl Default for TextNormalizerConfig {
    fn default() -> Self {
        Self {
            lowercase: true,
            remove_punctuation: false,
            expand_abbreviations: true,
            normalize_numbers: true,
            normalize_whitespace: true,
        }
    }
}

/// Text normalizer for preprocessing text before TTS
#[derive(Debug)]
pub struct TextNormalizer {
    config: TextNormalizerConfig,
    abbreviation_map: HashMap<String, String>,
    number_words: Vec<&'static str>,
    tens_words: Vec<&'static str>,
}

impl TextNormalizer {
    /// Create a new text normalizer with the given configuration
    #[must_use]
    pub fn new(config: TextNormalizerConfig) -> Self {
        let mut abbreviation_map = HashMap::new();

        // Common abbreviations
        abbreviation_map.insert("Dr.".to_string(), "Doctor".to_string());
        abbreviation_map.insert("Mr.".to_string(), "Mister".to_string());
        abbreviation_map.insert("Mrs.".to_string(), "Missus".to_string());
        abbreviation_map.insert("Ms.".to_string(), "Miss".to_string());
        abbreviation_map.insert("St.".to_string(), "Street".to_string());
        abbreviation_map.insert("Ave.".to_string(), "Avenue".to_string());
        abbreviation_map.insert("Rd.".to_string(), "Road".to_string());
        abbreviation_map.insert("Blvd.".to_string(), "Boulevard".to_string());
        abbreviation_map.insert("Inc.".to_string(), "Incorporated".to_string());
        abbreviation_map.insert("Ltd.".to_string(), "Limited".to_string());
        abbreviation_map.insert("Co.".to_string(), "Company".to_string());
        abbreviation_map.insert("Corp.".to_string(), "Corporation".to_string());
        abbreviation_map.insert("Jr.".to_string(), "Junior".to_string());
        abbreviation_map.insert("Sr.".to_string(), "Senior".to_string());
        abbreviation_map.insert("etc.".to_string(), "et cetera".to_string());
        abbreviation_map.insert("vs.".to_string(), "versus".to_string());
        abbreviation_map.insert("i.e.".to_string(), "that is".to_string());
        abbreviation_map.insert("e.g.".to_string(), "for example".to_string());

        let number_words = vec![
            "zero",
            "one",
            "two",
            "three",
            "four",
            "five",
            "six",
            "seven",
            "eight",
            "nine",
            "ten",
            "eleven",
            "twelve",
            "thirteen",
            "fourteen",
            "fifteen",
            "sixteen",
            "seventeen",
            "eighteen",
            "nineteen",
        ];

        let tens_words = vec![
            "", "", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety",
        ];

        Self {
            config,
            abbreviation_map,
            number_words,
            tens_words,
        }
    }

    /// Create a normalizer with default configuration
    #[must_use]
    pub fn default() -> Self {
        Self::new(TextNormalizerConfig::default())
    }

    /// Get the configuration
    #[must_use]
    pub fn config(&self) -> &TextNormalizerConfig {
        &self.config
    }

    /// Normalize text according to the configuration
    ///
    /// # Errors
    ///
    /// Returns error if text processing fails
    pub fn normalize(&self, text: &str) -> Result<String> {
        let mut result = text.to_string();

        // Unicode normalization (NFC - canonical decomposition followed by canonical composition)
        result = result.nfc().collect::<String>();

        // Expand abbreviations
        if self.config.expand_abbreviations {
            result = self.expand_abbreviations(&result)?;
        }

        // Handle special characters (must be before number normalization)
        result = self.handle_special_chars(&result)?;

        // Normalize numbers
        if self.config.normalize_numbers {
            result = self.normalize_numbers(&result)?;
        }

        // Case normalization
        if self.config.lowercase {
            result = result.to_lowercase();
        }

        // Remove punctuation
        if self.config.remove_punctuation {
            result = self.remove_punctuation(&result);
        }

        // Normalize whitespace
        if self.config.normalize_whitespace {
            result = self.normalize_whitespace(&result);
        }

        Ok(result)
    }

    /// Expand common abbreviations
    fn expand_abbreviations(&self, text: &str) -> Result<String> {
        let mut result = text.to_string();

        for (abbr, expansion) in &self.abbreviation_map {
            // Case-insensitive replacement
            let pattern = regex::escape(abbr);
            // For abbreviations ending with period, use space or end of string as boundary
            let re = if abbr.ends_with('.') {
                Regex::new(&format!(r"(?i)\b{pattern}(?:\s|$)"))
                    .map_err(|e| TtsError::TextProcessing(format!("Regex error: {e}")))?
            } else {
                Regex::new(&format!(r"(?i)\b{pattern}\b"))
                    .map_err(|e| TtsError::TextProcessing(format!("Regex error: {e}")))?
            };

            // Preserve the trailing space if it exists
            result = re
                .replace_all(&result, |caps: &regex::Captures| {
                    let matched = &caps[0];
                    if matched.ends_with(' ') {
                        format!("{} ", expansion)
                    } else {
                        expansion.to_string()
                    }
                })
                .to_string();
        }

        Ok(result)
    }

    /// Convert numbers to words
    fn normalize_numbers(&self, text: &str) -> Result<String> {
        let re = Regex::new(r"\b\d+\b")
            .map_err(|e| TtsError::TextProcessing(format!("Regex error: {e}")))?;

        let result = re.replace_all(text, |caps: &regex::Captures| {
            let num_str = &caps[0];
            if let Ok(num) = num_str.parse::<i32>() {
                self.number_to_words(num)
            } else {
                num_str.to_string()
            }
        });

        Ok(result.to_string())
    }

    /// Convert a number to its word representation
    fn number_to_words(&self, num: i32) -> String {
        if num < 0 {
            return format!("minus {}", self.number_to_words(-num));
        }

        if num < 20 {
            return self.number_words[num as usize].to_string();
        }

        if num < 100 {
            let tens = num / 10;
            let ones = num % 10;
            if ones == 0 {
                return self.tens_words[tens as usize].to_string();
            }
            return format!(
                "{} {}",
                self.tens_words[tens as usize], self.number_words[ones as usize]
            );
        }

        if num < 1000 {
            let hundreds = num / 100;
            let remainder = num % 100;
            if remainder == 0 {
                return format!("{} hundred", self.number_words[hundreds as usize]);
            }
            return format!(
                "{} hundred {}",
                self.number_words[hundreds as usize],
                self.number_to_words(remainder)
            );
        }

        if num < 1_000_000 {
            let thousands = num / 1000;
            let remainder = num % 1000;
            if remainder == 0 {
                return format!("{} thousand", self.number_to_words(thousands));
            }
            return format!(
                "{} thousand {}",
                self.number_to_words(thousands),
                self.number_to_words(remainder)
            );
        }

        // For larger numbers, just return the digit string
        num.to_string()
    }

    /// Handle special characters (currency, percentages, etc.)
    fn handle_special_chars(&self, text: &str) -> Result<String> {
        let mut result = text.to_string();

        // Currency symbols
        let currency_re = Regex::new(r"\$(\d+)")
            .map_err(|e| TtsError::TextProcessing(format!("Regex error: {e}")))?;
        result = currency_re.replace_all(&result, "$1 dollars").to_string();

        // Percentages
        let percent_re = Regex::new(r"(\d+)%")
            .map_err(|e| TtsError::TextProcessing(format!("Regex error: {e}")))?;
        result = percent_re.replace_all(&result, "$1 percent").to_string();

        // Degrees
        let degree_re = Regex::new(r"(\d+)°")
            .map_err(|e| TtsError::TextProcessing(format!("Regex error: {e}")))?;
        result = degree_re.replace_all(&result, "$1 degrees").to_string();

        Ok(result)
    }

    /// Remove punctuation marks
    fn remove_punctuation(&self, text: &str) -> String {
        text.chars().filter(|c| !c.is_ascii_punctuation()).collect()
    }

    /// Normalize whitespace (collapse multiple spaces into one)
    fn normalize_whitespace(&self, text: &str) -> String {
        text.split_whitespace().collect::<Vec<_>>().join(" ")
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_default_config() {
        let config = TextNormalizerConfig::default();
        assert!(config.lowercase);
        assert!(!config.remove_punctuation);
        assert!(config.expand_abbreviations);
        assert!(config.normalize_numbers);
        assert!(config.normalize_whitespace);
    }

    #[test]
    fn test_normalizer_creation() {
        let normalizer = TextNormalizer::default();
        assert!(normalizer.config.lowercase);
    }

    #[test]
    fn test_lowercase_normalization() {
        let config = TextNormalizerConfig {
            lowercase: true,
            remove_punctuation: false,
            expand_abbreviations: false,
            normalize_numbers: false,
            normalize_whitespace: false,
        };
        let normalizer = TextNormalizer::new(config);
        let result = normalizer.normalize("Hello World").unwrap();
        assert_eq!(result, "hello world");
    }

    #[test]
    fn test_abbreviation_expansion() {
        let config = TextNormalizerConfig {
            lowercase: false,
            remove_punctuation: false,
            expand_abbreviations: true,
            normalize_numbers: false,
            normalize_whitespace: false,
        };
        let normalizer = TextNormalizer::new(config);

        let result = normalizer.normalize("Dr. Smith lives on Main St.").unwrap();
        assert_eq!(result, "Doctor Smith lives on Main Street");

        let result = normalizer.normalize("Mr. Jones works at ABC Inc.").unwrap();
        assert_eq!(result, "Mister Jones works at ABC Incorporated");
    }

    #[test]
    fn test_number_to_words() {
        let normalizer = TextNormalizer::default();

        assert_eq!(normalizer.number_to_words(0), "zero");
        assert_eq!(normalizer.number_to_words(5), "five");
        assert_eq!(normalizer.number_to_words(13), "thirteen");
        assert_eq!(normalizer.number_to_words(20), "twenty");
        assert_eq!(normalizer.number_to_words(42), "forty two");
        assert_eq!(normalizer.number_to_words(99), "ninety nine");
        assert_eq!(normalizer.number_to_words(100), "one hundred");
        assert_eq!(normalizer.number_to_words(256), "two hundred fifty six");
        assert_eq!(normalizer.number_to_words(1000), "one thousand");
        assert_eq!(
            normalizer.number_to_words(1234),
            "one thousand two hundred thirty four"
        );
        assert_eq!(normalizer.number_to_words(-5), "minus five");
    }

    #[test]
    fn test_number_normalization() {
        let config = TextNormalizerConfig {
            lowercase: false,
            remove_punctuation: false,
            expand_abbreviations: false,
            normalize_numbers: true,
            normalize_whitespace: false,
        };
        let normalizer = TextNormalizer::new(config);

        let result = normalizer
            .normalize("I have 3 apples and 42 oranges.")
            .unwrap();
        assert_eq!(result, "I have three apples and forty two oranges.");

        let result = normalizer.normalize("The year 2024 was great.").unwrap();
        assert_eq!(result, "The year two thousand twenty four was great.");
    }

    #[test]
    fn test_special_chars_currency() {
        let config = TextNormalizerConfig {
            lowercase: false,
            remove_punctuation: false,
            expand_abbreviations: false,
            normalize_numbers: false,
            normalize_whitespace: false,
        };
        let normalizer = TextNormalizer::new(config);

        let result = normalizer.normalize("The price is $50.").unwrap();
        assert_eq!(result, "The price is 50 dollars.");
    }

    #[test]
    fn test_special_chars_percentage() {
        let config = TextNormalizerConfig {
            lowercase: false,
            remove_punctuation: false,
            expand_abbreviations: false,
            normalize_numbers: false,
            normalize_whitespace: false,
        };
        let normalizer = TextNormalizer::new(config);

        let result = normalizer.normalize("Success rate is 95%.").unwrap();
        assert_eq!(result, "Success rate is 95 percent.");
    }

    #[test]
    fn test_special_chars_degrees() {
        let config = TextNormalizerConfig {
            lowercase: false,
            remove_punctuation: false,
            expand_abbreviations: false,
            normalize_numbers: false,
            normalize_whitespace: false,
        };
        let normalizer = TextNormalizer::new(config);

        let result = normalizer.normalize("Temperature is 25°.").unwrap();
        assert_eq!(result, "Temperature is 25 degrees.");
    }

    #[test]
    fn test_punctuation_removal() {
        let config = TextNormalizerConfig {
            lowercase: false,
            remove_punctuation: true,
            expand_abbreviations: false,
            normalize_numbers: false,
            normalize_whitespace: false,
        };
        let normalizer = TextNormalizer::new(config);

        let result = normalizer.normalize("Hello, world! How are you?").unwrap();
        assert_eq!(result, "Hello world How are you");
    }

    #[test]
    fn test_whitespace_normalization() {
        let config = TextNormalizerConfig {
            lowercase: false,
            remove_punctuation: false,
            expand_abbreviations: false,
            normalize_numbers: false,
            normalize_whitespace: true,
        };
        let normalizer = TextNormalizer::new(config);

        let result = normalizer.normalize("Hello    world   test").unwrap();
        assert_eq!(result, "Hello world test");

        let result = normalizer.normalize("  Leading and trailing  ").unwrap();
        assert_eq!(result, "Leading and trailing");
    }

    #[test]
    fn test_full_normalization() {
        let config = TextNormalizerConfig {
            lowercase: true,
            remove_punctuation: true,
            expand_abbreviations: true,
            normalize_numbers: true,
            normalize_whitespace: true,
        };
        let normalizer = TextNormalizer::new(config);

        let result = normalizer
            .normalize("Dr. Smith said I have 3 apples for 5 dollars")
            .unwrap();
        assert_eq!(
            result,
            "doctor smith said i have three apples for five dollars"
        );
    }

    #[test]
    fn test_unicode_normalization() {
        let normalizer = TextNormalizer::default();

        // Combining characters should be normalized
        let result = normalizer.normalize("café").unwrap();
        assert!(result.contains('é') || result.contains("cafe"));
    }

    #[test]
    fn test_multiple_abbreviations() {
        let config = TextNormalizerConfig {
            lowercase: false,
            remove_punctuation: false,
            expand_abbreviations: true,
            normalize_numbers: false,
            normalize_whitespace: false,
        };
        let normalizer = TextNormalizer::new(config);

        let result = normalizer
            .normalize("Mr. and Mrs. Smith live on Oak St.")
            .unwrap();
        assert_eq!(result, "Mister and Missus Smith live on Oak Street");
    }

    #[test]
    fn test_combined_normalization() {
        let config = TextNormalizerConfig {
            lowercase: true,
            remove_punctuation: false,
            expand_abbreviations: true,
            normalize_numbers: true,
            normalize_whitespace: true,
        };
        let normalizer = TextNormalizer::new(config);

        let result = normalizer
            .normalize("Dr.   Smith   has   42   patients.")
            .unwrap();
        assert_eq!(result, "doctor smith has forty two patients.");
    }
}