//! CJK (Chinese, Japanese, Korean) language support for OCR
//!
//! This module provides comprehensive support for CJK languages including
//! character detection, text segmentation, and language-specific processing.

use crate::utils::Result;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

/// CJK language variants
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum CJKLanguage {
    ChineseSimplified,
    ChineseTraditional,
    Japanese,
    Korean,
    Vietnamese,
}

/// CJK character categories
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum CJKCharacterCategory {
    // Chinese characters
    ChineseSimplified,
    ChineseTraditional,
    ChineseCommon, // Characters common to both simplified and traditional

    // Japanese characters
    Hiragana,
    Katakana,
    Kanji, // Chinese characters used in Japanese

    // Korean characters
    HangulSyllables,
    HangulJamo,
    HangulCompatibilityJamo,

    // Punctuation and symbols
    CJKPunctuation,
    CJKSymbols,
    CJKRadicals,
    CJKStrokes,
}

/// CJK text segmentation result
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CJKSegmentationResult {
    pub segments: Vec<CJKSegment>,
    pub language: CJKLanguage,
    pub confidence: f32,
}

/// A segment of CJK text
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CJKSegment {
    pub text: String,
    pub start_pos: usize,
    pub end_pos: usize,
    pub category: CJKCharacterCategory,
    pub confidence: f32,
}

/// CJK text processor
pub struct CJKProcessor {
    chinese_dictionary: Option<ChineseDictionary>,
    japanese_dictionary: Option<JapaneseDictionary>,
    korean_dictionary: Option<KoreanDictionary>,
}

impl CJKProcessor {
    /// Create a new CJK processor
    pub fn new() -> Self {
        Self {
            chinese_dictionary: None,
            japanese_dictionary: None,
            korean_dictionary: None,
        }
    }

    /// Load Chinese dictionary
    pub async fn load_chinese_dictionary(&mut self, path: &str) -> Result<()> {
        // TODO: Implement Chinese dictionary loading
        self.chinese_dictionary = Some(ChineseDictionary::new());
        Ok(())
    }

    /// Load Japanese dictionary
    pub async fn load_japanese_dictionary(&mut self, path: &str) -> Result<()> {
        // TODO: Implement Japanese dictionary loading
        self.japanese_dictionary = Some(JapaneseDictionary::new());
        Ok(())
    }

    /// Load Korean dictionary
    pub async fn load_korean_dictionary(&mut self, path: &str) -> Result<()> {
        // TODO: Implement Korean dictionary loading
        self.korean_dictionary = Some(KoreanDictionary::new());
        Ok(())
    }

    /// Detect CJK language from text
    pub fn detect_cjk_language(&self, text: &str) -> Vec<(CJKLanguage, f32)> {
        let mut scores = HashMap::new();

        for c in text.chars() {
            if Self::is_chinese_character(c) {
                *scores.entry(CJKLanguage::ChineseSimplified).or_insert(0.0) += 1.0;
                *scores.entry(CJKLanguage::ChineseTraditional).or_insert(0.0) += 1.0;
            } else if Self::is_japanese_character(c) {
                *scores.entry(CJKLanguage::Japanese).or_insert(0.0) += 1.0;
            } else if Self::is_korean_character(c) {
                *scores.entry(CJKLanguage::Korean).or_insert(0.0) += 1.0;
            }
        }

        let total_chars = text.chars().count() as f32;
        if total_chars == 0.0 {
            return vec![];
        }

        scores
            .into_iter()
            .map(|(lang, score)| (lang, score / total_chars))
            .collect()
    }

    /// Segment CJK text
    pub fn segment_text(&self, text: &str, language: CJKLanguage) -> Result<CJKSegmentationResult> {
        match language {
            CJKLanguage::ChineseSimplified | CJKLanguage::ChineseTraditional => {
                self.segment_chinese(text, language)
            }
            CJKLanguage::Japanese => self.segment_japanese(text),
            CJKLanguage::Korean => self.segment_korean(text),
            CJKLanguage::Vietnamese => self.segment_vietnamese(text),
        }
    }

    /// Segment Chinese text
    fn segment_chinese(&self, text: &str, language: CJKLanguage) -> Result<CJKSegmentationResult> {
        let mut segments = Vec::new();
        let mut current_segment = String::new();
        let mut start_pos = 0;

        for (i, c) in text.char_indices() {
            if Self::is_chinese_character(c) {
                if current_segment.is_empty() {
                    start_pos = i;
                }
                current_segment.push(c);
            } else {
                if !current_segment.is_empty() {
                    let category = match language {
                        CJKLanguage::ChineseSimplified => CJKCharacterCategory::ChineseSimplified,
                        CJKLanguage::ChineseTraditional => CJKCharacterCategory::ChineseTraditional,
                        _ => CJKCharacterCategory::ChineseCommon,
                    };

                    segments.push(CJKSegment {
                        text: current_segment.clone(),
                        start_pos,
                        end_pos: i,
                        category,
                        confidence: 1.0,
                    });
                    current_segment.clear();
                }
            }
        }

        // Handle last segment
        if !current_segment.is_empty() {
            let category = match language {
                CJKLanguage::ChineseSimplified => CJKCharacterCategory::ChineseSimplified,
                CJKLanguage::ChineseTraditional => CJKCharacterCategory::ChineseTraditional,
                _ => CJKCharacterCategory::ChineseCommon,
            };

            segments.push(CJKSegment {
                text: current_segment,
                start_pos,
                end_pos: text.len(),
                category,
                confidence: 1.0,
            });
        }

        Ok(CJKSegmentationResult {
            segments,
            language,
            confidence: 1.0,
        })
    }

    /// Segment Japanese text
    fn segment_japanese(&self, text: &str) -> Result<CJKSegmentationResult> {
        let mut segments = Vec::new();
        let mut current_segment = String::new();
        let mut start_pos = 0;
        let mut current_category = None;

        for (i, c) in text.char_indices() {
            let category = if Self::is_hiragana(c) {
                Some(CJKCharacterCategory::Hiragana)
            } else if Self::is_katakana(c) {
                Some(CJKCharacterCategory::Katakana)
            } else if Self::is_kanji(c) {
                Some(CJKCharacterCategory::Kanji)
            } else {
                None
            };

            if let Some(cat) = category {
                if current_category == Some(cat) {
                    current_segment.push(c);
                } else {
                    if !current_segment.is_empty() {
                        segments.push(CJKSegment {
                            text: current_segment.clone(),
                            start_pos,
                            end_pos: i,
                            category: current_category.unwrap(),
                            confidence: 1.0,
                        });
                    }
                    current_segment = c.to_string();
                    start_pos = i;
                    current_category = Some(cat);
                }
            } else {
                if !current_segment.is_empty() {
                    segments.push(CJKSegment {
                        text: current_segment.clone(),
                        start_pos,
                        end_pos: i,
                        category: current_category.unwrap(),
                        confidence: 1.0,
                    });
                    current_segment.clear();
                    current_category = None;
                }
            }
        }

        // Handle last segment
        if !current_segment.is_empty() {
            segments.push(CJKSegment {
                text: current_segment,
                start_pos,
                end_pos: text.len(),
                category: current_category.unwrap(),
                confidence: 1.0,
            });
        }

        Ok(CJKSegmentationResult {
            segments,
            language: CJKLanguage::Japanese,
            confidence: 1.0,
        })
    }

    /// Segment Korean text
    fn segment_korean(&self, text: &str) -> Result<CJKSegmentationResult> {
        let mut segments = Vec::new();
        let mut current_segment = String::new();
        let mut start_pos = 0;

        for (i, c) in text.char_indices() {
            if Self::is_korean_character(c) {
                if current_segment.is_empty() {
                    start_pos = i;
                }
                current_segment.push(c);
            } else {
                if !current_segment.is_empty() {
                    let category =
                        if Self::is_hangul_syllable(current_segment.chars().next().unwrap()) {
                            CJKCharacterCategory::HangulSyllables
                        } else {
                            CJKCharacterCategory::HangulJamo
                        };

                    segments.push(CJKSegment {
                        text: current_segment.clone(),
                        start_pos,
                        end_pos: i,
                        category,
                        confidence: 1.0,
                    });
                    current_segment.clear();
                }
            }
        }

        // Handle last segment
        if !current_segment.is_empty() {
            let category = if Self::is_hangul_syllable(current_segment.chars().next().unwrap()) {
                CJKCharacterCategory::HangulSyllables
            } else {
                CJKCharacterCategory::HangulJamo
            };

            segments.push(CJKSegment {
                text: current_segment,
                start_pos,
                end_pos: text.len(),
                category,
                confidence: 1.0,
            });
        }

        Ok(CJKSegmentationResult {
            segments,
            language: CJKLanguage::Korean,
            confidence: 1.0,
        })
    }

    /// Segment Vietnamese text
    fn segment_vietnamese(&self, text: &str) -> Result<CJKSegmentationResult> {
        // Vietnamese uses Latin script with diacritics
        // For now, treat as regular text segmentation
        Ok(CJKSegmentationResult {
            segments: vec![CJKSegment {
                text: text.to_string(),
                start_pos: 0,
                end_pos: text.len(),
                category: CJKCharacterCategory::CJKSymbols, // Placeholder
                confidence: 1.0,
            }],
            language: CJKLanguage::Vietnamese,
            confidence: 1.0,
        })
    }

    /// Check if a character is Chinese
    pub fn is_chinese_character(c: char) -> bool {
        let code = c as u32;
        matches!(
            code,
            0x4E00..=0x9FFF | // CJK Unified Ideographs
            0x3400..=0x4DBF | // CJK Unified Ideographs Extension A
            0x20000..=0x2A6DF | // CJK Unified Ideographs Extension B
            0x2A700..=0x2B73F | // CJK Unified Ideographs Extension C
            0x2B740..=0x2B81F | // CJK Unified Ideographs Extension D
            0x2B820..=0x2CEAF | // CJK Unified Ideographs Extension E
            0x2CEB0..=0x2EBEF | // CJK Unified Ideographs Extension F
            0x30000..=0x3134F | // CJK Unified Ideographs Extension G
            0x31350..=0x323AF | // CJK Unified Ideographs Extension H
            0x323B0..=0x32B2F   // CJK Unified Ideographs Extension I
        )
    }

    /// Check if a character is Japanese Hiragana
    pub fn is_hiragana(c: char) -> bool {
        let code = c as u32;
        matches!(code, 0x3040..=0x309F)
    }

    /// Check if a character is Japanese Katakana
    pub fn is_katakana(c: char) -> bool {
        let code = c as u32;
        matches!(code, 0x30A0..=0x30FF)
    }

    /// Check if a character is Japanese Kanji
    pub fn is_kanji(c: char) -> bool {
        Self::is_chinese_character(c) // Kanji are Chinese characters used in Japanese
    }

    /// Check if a character is Japanese
    pub fn is_japanese_character(c: char) -> bool {
        Self::is_hiragana(c) || Self::is_katakana(c) || Self::is_kanji(c)
    }

    /// Check if a character is Korean
    pub fn is_korean_character(c: char) -> bool {
        let code = c as u32;
        matches!(
            code,
            0xAC00..=0xD7AF | // Hangul Syllables
            0x1100..=0x11FF | // Hangul Jamo
            0x3130..=0x318F   // Hangul Compatibility Jamo
        )
    }

    /// Check if a character is Hangul syllable
    pub fn is_hangul_syllable(c: char) -> bool {
        let code = c as u32;
        matches!(code, 0xAC00..=0xD7AF)
    }

    /// Check if a character is CJK
    pub fn is_cjk_character(c: char) -> bool {
        Self::is_chinese_character(c)
            || Self::is_japanese_character(c)
            || Self::is_korean_character(c)
    }

    /// Get character category
    pub fn get_character_category(c: char) -> Option<CJKCharacterCategory> {
        if Self::is_chinese_character(c) {
            Some(CJKCharacterCategory::ChineseCommon)
        } else if Self::is_hiragana(c) {
            Some(CJKCharacterCategory::Hiragana)
        } else if Self::is_katakana(c) {
            Some(CJKCharacterCategory::Katakana)
        } else if Self::is_kanji(c) {
            Some(CJKCharacterCategory::Kanji)
        } else if Self::is_hangul_syllable(c) {
            Some(CJKCharacterCategory::HangulSyllables)
        } else if Self::is_korean_character(c) {
            Some(CJKCharacterCategory::HangulJamo)
        } else {
            None
        }
    }
}

/// Chinese dictionary (placeholder)
pub struct ChineseDictionary {
    words: Vec<String>,
}

impl ChineseDictionary {
    pub fn new() -> Self {
        Self { words: Vec::new() }
    }
}

/// Japanese dictionary (placeholder)
pub struct JapaneseDictionary {
    words: Vec<String>,
}

impl JapaneseDictionary {
    pub fn new() -> Self {
        Self { words: Vec::new() }
    }
}

/// Korean dictionary (placeholder)
pub struct KoreanDictionary {
    words: Vec<String>,
}

impl KoreanDictionary {
    pub fn new() -> Self {
        Self { words: Vec::new() }
    }
}

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

    #[test]
    fn test_cjk_character_detection() {
        assert!(CJKProcessor::is_chinese_character('中'));
        assert!(CJKProcessor::is_hiragana('ひ'));
        assert!(CJKProcessor::is_katakana('カ'));
        assert!(CJKProcessor::is_korean_character('한'));
        assert!(CJKProcessor::is_cjk_character('中'));
        assert!(CJKProcessor::is_cjk_character('ひ'));
        assert!(CJKProcessor::is_cjk_character('한'));
    }

    #[test]
    fn test_language_detection() {
        let processor = CJKProcessor::new();
        let scores = processor.detect_cjk_language("中文");
        assert!(scores
            .iter()
            .any(|(lang, _)| *lang == CJKLanguage::ChineseSimplified));

        let scores = processor.detect_cjk_language("ひらがな");
        assert!(scores
            .iter()
            .any(|(lang, _)| *lang == CJKLanguage::Japanese));

        let scores = processor.detect_cjk_language("한글");
        assert!(scores.iter().any(|(lang, _)| *lang == CJKLanguage::Korean));
    }

    #[test]
    fn test_text_segmentation() {
        let processor = CJKProcessor::new();

        // Test Chinese segmentation
        let result = processor
            .segment_text("中文测试", CJKLanguage::ChineseSimplified)
            .unwrap();
        assert_eq!(result.language, CJKLanguage::ChineseSimplified);
        assert!(!result.segments.is_empty());

        // Test Japanese segmentation
        let result = processor
            .segment_text("ひらがなカタカナ", CJKLanguage::Japanese)
            .unwrap();
        assert_eq!(result.language, CJKLanguage::Japanese);
        assert!(!result.segments.is_empty());

        // Test Korean segmentation
        let result = processor
            .segment_text("한글테스트", CJKLanguage::Korean)
            .unwrap();
        assert_eq!(result.language, CJKLanguage::Korean);
        assert!(!result.segments.is_empty());
    }
}
