use std::path::{Path, PathBuf};

use tantivy::schema::{
    Field, IndexRecordOption, JsonObjectOptions, Schema, Term, TextFieldIndexing, TextOptions,
    INDEXED, STORED, STRING,
};
use tantivy::tokenizer::{
    AsciiFoldingFilter, LowerCaser, NgramTokenizer, RawTokenizer, RemoveLongFilter,
    SimpleTokenizer, TextAnalyzer, TokenStream,
};
use tantivy::Index;

pub const F_PG_ID: &str = "pg_id";
pub const F_TABLE_NAME: &str = "table_name";
pub const F_ROW_KEY: &str = "row_key";
pub const F_ALL_TEXT: &str = "all_text";
pub const F_DATA_WORD: &str = "data_word";
pub const F_DATA_NGRAM: &str = "data_ngram";
pub const F_DATA_EXACT: &str = "data_exact";

pub const TOK_WORD: &str = "kw_word";
pub const TOK_NGRAM: &str = "kw_ngram";
pub const TOK_EXACT: &str = "kw_exact";

/// Returns the on-disk path for a profile search index.
pub fn search_index_path(root: &Path, profile_name: &str) -> PathBuf {
    root.join(profile_name)
}

/// Returns the unique index key for one table row inside a profile index.
pub fn search_row_key(table_name: &str, row_id: i64) -> String {
    format!("{}:{}", table_name, row_id)
}

/// Normalizes user-entered values for exact-mode terms.
pub fn normalize_exact(input: &str) -> String {
    let trimmed = input.trim();
    if trimmed.is_empty() {
        return String::new();
    }

    let mut analyzer = exact_analyzer();
    let mut stream = analyzer.token_stream(trimmed);
    let mut out = String::with_capacity(trimmed.len());
    while let Some(token) = stream.next() {
        out.push_str(&token.text);
    }
    out
}

/// Normalizes a column name to the JSON-key form used at index time.
pub fn normalize_column_name(column: &str) -> String {
    column.to_ascii_lowercase()
}

/// Creates the column-aware search schema.
pub fn create_search_schema() -> Schema {
    let mut schema_builder = Schema::builder();

    schema_builder.add_u64_field(F_PG_ID, INDEXED | STORED);
    schema_builder.add_text_field(F_TABLE_NAME, STRING | STORED);
    schema_builder.add_text_field(F_ROW_KEY, STRING | STORED);
    schema_builder.add_text_field(F_ALL_TEXT, text_options(TOK_WORD));

    schema_builder.add_json_field(F_DATA_WORD, json_options(TOK_WORD, true, false));
    schema_builder.add_json_field(F_DATA_NGRAM, json_options(TOK_NGRAM, true, false));
    schema_builder.add_json_field(F_DATA_EXACT, json_options(TOK_EXACT, false, false));

    schema_builder.build()
}

fn text_options(tokenizer_name: &str) -> TextOptions {
    let indexing = TextFieldIndexing::default()
        .set_tokenizer(tokenizer_name)
        .set_index_option(IndexRecordOption::WithFreqsAndPositions);

    TextOptions::default().set_indexing_options(indexing)
}

fn json_options(tokenizer_name: &str, with_positions: bool, stored: bool) -> JsonObjectOptions {
    let index_option = if with_positions {
        IndexRecordOption::WithFreqsAndPositions
    } else {
        IndexRecordOption::Basic
    };

    let indexing = TextFieldIndexing::default()
        .set_tokenizer(tokenizer_name)
        .set_index_option(index_option);

    let mut options = JsonObjectOptions::default().set_indexing_options(indexing);
    if stored {
        options = options.set_stored();
    }
    options
}

/// Registers all required tokenizers with the index.
pub fn register_tokenizers(index: &Index) -> tantivy::Result<()> {
    let tokenizer_manager = index.tokenizers();

    tokenizer_manager.register(TOK_WORD, word_analyzer());
    tokenizer_manager.register(TOK_NGRAM, ngram_analyzer()?);
    tokenizer_manager.register(TOK_EXACT, exact_analyzer());

    Ok(())
}

fn word_analyzer() -> TextAnalyzer {
    TextAnalyzer::builder(SimpleTokenizer::default())
        .filter(RemoveLongFilter::limit(80))
        .filter(LowerCaser)
        .filter(AsciiFoldingFilter)
        .build()
}

fn ngram_analyzer() -> tantivy::Result<TextAnalyzer> {
    Ok(TextAnalyzer::builder(NgramTokenizer::new(3, 3, false)?)
        .filter(RemoveLongFilter::limit(80))
        .filter(LowerCaser)
        .filter(AsciiFoldingFilter)
        .build())
}

fn exact_analyzer() -> TextAnalyzer {
    TextAnalyzer::builder(RawTokenizer::default())
        .filter(LowerCaser)
        .filter(AsciiFoldingFilter)
        .build()
}

/// Tokenizes text the same way `data_word` is indexed.
pub fn tokenize_word(text: &str) -> Vec<String> {
    tokenize_with(word_analyzer(), text)
}

/// Tokenizes text the same way `data_ngram` is indexed.
pub fn tokenize_ngram(text: &str) -> Vec<String> {
    match ngram_analyzer() {
        Ok(analyzer) => tokenize_with(analyzer, text),
        Err(_) => Vec::new(),
    }
}

fn tokenize_with(mut analyzer: TextAnalyzer, text: &str) -> Vec<String> {
    let mut stream = analyzer.token_stream(text);
    let mut out = Vec::new();
    while let Some(token) = stream.next() {
        out.push(token.text.clone());
    }
    out
}

/// Builds a term scoped to a specific JSON path within a JSON field.
pub fn json_path_term(field: Field, column: &str, text: &str) -> Term {
    let mut term = Term::from_field_json_path(field, column, false);
    term.append_type_and_str(text);
    term
}

/// Returns all required schema fields or fails loudly on mismatch.
pub struct SchemaFields {
    pub pg_id: Field,
    pub table_name: Field,
    pub row_key: Field,
    pub all_text: Field,
    pub data_word: Field,
    pub data_ngram: Field,
    pub data_exact: Field,
}

impl SchemaFields {
    pub fn from(schema: &Schema) -> tantivy::Result<Self> {
        Ok(Self {
            pg_id: get_field(schema, F_PG_ID)?,
            table_name: get_field(schema, F_TABLE_NAME)?,
            row_key: get_field(schema, F_ROW_KEY)?,
            all_text: get_field(schema, F_ALL_TEXT)?,
            data_word: get_field(schema, F_DATA_WORD)?,
            data_ngram: get_field(schema, F_DATA_NGRAM)?,
            data_exact: get_field(schema, F_DATA_EXACT)?,
        })
    }
}

fn get_field(schema: &Schema, name: &str) -> tantivy::Result<Field> {
    schema.get_field(name).map_err(|e| {
        tantivy::TantivyError::SchemaError(format!("schema is missing field '{name}': {e}"))
    })
}