use std::sync::Arc;

use serde::{Deserialize, Serialize};

use crate::db::{NormalizedFields, SimilarAlbum, SimilarArtist};
use crate::web::AppState;

use super::metadata::RawMetadata;

#[derive(Debug)]
pub struct FolderContext {
    pub folder_path: String,      // path relative to inbox_dir (e.g. "Kunteynir/Синглы/Пьюк")
    pub folder_files: Vec<String>, // audio filenames in the same folder
    pub track_count: usize,        // number of audio files in folder
}

/// Build the user message with all context and call Ollama for normalization.
pub async fn normalize(
    state: &Arc<AppState>,
    raw: &RawMetadata,
    hints: &crate::db::PathHints,
    similar_artists: &[SimilarArtist],
    similar_albums: &[SimilarAlbum],
    folder_ctx: Option<&FolderContext>,
) -> anyhow::Result<NormalizedFields> {
    let user_message = build_user_message(raw, hints, similar_artists, similar_albums, folder_ctx);

    let schema = normalize_schema();
    let response = call_ollama(
        &state.config.ollama_url,
        &state.config.ollama_model,
        &state.system_prompt,
        &user_message,
        state.config.ollama_auth.as_deref(),
        0.5,
        512,
        Some(("normalized_metadata", schema.clone())),
    )
    .await?;

    match parse_response(&response) {
        Ok(fields) => Ok(fields),
        Err(e) => {
            tracing::warn!(error = %e, "LLM parse failed, retrying with higher frequency_penalty");
            let response2 = call_ollama(
                &state.config.ollama_url,
                &state.config.ollama_model,
                &state.system_prompt,
                &user_message,
                state.config.ollama_auth.as_deref(),
                1.5,
                512,
                Some(("normalized_metadata", schema)),
            )
            .await?;
            parse_response(&response2)
        }
    }
}

fn build_user_message(
    raw: &RawMetadata,
    hints: &crate::db::PathHints,
    similar_artists: &[SimilarArtist],
    similar_albums: &[SimilarAlbum],
    folder_ctx: Option<&FolderContext>,
) -> String {
    let mut msg = String::from("## Raw metadata from file tags\n");

    if let Some(v) = &raw.title {
        msg.push_str(&format!("Title: \"{}\"\n", v));
    }
    if let Some(v) = &raw.artist {
        msg.push_str(&format!("Artist: \"{}\"\n", v));
    }
    if let Some(v) = &raw.album {
        msg.push_str(&format!("Album: \"{}\"\n", v));
    }
    if let Some(v) = raw.year {
        msg.push_str(&format!("Year: {}\n", v));
    }
    if let Some(v) = raw.track_number {
        msg.push_str(&format!("Track number: {}\n", v));
    }
    if let Some(v) = &raw.genre {
        msg.push_str(&format!("Genre: \"{}\"\n", v));
    }

    msg.push_str("\n## Hints from file path\n");
    if let Some(v) = &hints.artist {
        msg.push_str(&format!("Path artist: \"{}\"\n", v));
    }
    if let Some(v) = &hints.album {
        msg.push_str(&format!("Path album: \"{}\"\n", v));
    }
    if let Some(v) = hints.year {
        msg.push_str(&format!("Path year: {}\n", v));
    }
    if let Some(v) = hints.track_number {
        msg.push_str(&format!("Path track number: {}\n", v));
    }
    if let Some(v) = &hints.title {
        msg.push_str(&format!("Path title: \"{}\"\n", v));
    }

    if !similar_artists.is_empty() {
        msg.push_str("\n## Existing artists in database (similar matches)\n");
        for a in similar_artists {
            msg.push_str(&format!("- \"{}\" (similarity: {:.2})\n", a.name, a.similarity));
        }
    }

    if !similar_albums.is_empty() {
        msg.push_str("\n## Existing albums in database (similar matches)\n");
        for a in similar_albums {
            let year_str = a.year.map(|y| format!(", year: {}", y)).unwrap_or_default();
            msg.push_str(&format!("- \"{}\" (similarity: {:.2}{})\n", a.name, a.similarity, year_str));
        }
    }

    if let Some(ctx) = folder_ctx {
        msg.push_str("\n## Folder context\n");
        msg.push_str(&format!("Folder path: \"{}\"\n", ctx.folder_path));
        msg.push_str(&format!("Track count in folder: {}\n", ctx.track_count));
        if !ctx.folder_files.is_empty() {
            msg.push_str("Files in folder:\n");
            for f in &ctx.folder_files {
                msg.push_str(&format!("  - {}\n", f));
            }
        }
    }

    msg
}

#[derive(Serialize)]
struct ChatRequest {
    model: String,
    messages: Vec<ChatMessage>,
    #[serde(skip_serializing_if = "Option::is_none")]
    response_format: Option<ChatResponseFormat>,
    stream: bool,
    temperature: f64,
    max_tokens: u32,
    frequency_penalty: f64,
}

#[derive(Serialize)]
struct ChatMessage {
    role: String,
    content: String,
}

#[derive(Serialize)]
struct ChatResponseFormat {
    #[serde(rename = "type")]
    kind: String,
    json_schema: JsonSchemaWrapper,
}

#[derive(Serialize)]
struct JsonSchemaWrapper {
    name: String,
    strict: bool,
    schema: serde_json::Value,
}

#[derive(Deserialize)]
struct ChatResponse {
    choices: Vec<ChatChoice>,
}

#[derive(Deserialize)]
struct ChatChoice {
    message: ChatResponseMessage,
}

#[derive(Deserialize)]
struct ChatResponseMessage {
    content: String,
}

pub async fn call_ollama(
    base_url: &str,
    model: &str,
    system_prompt: &str,
    user_message: &str,
    auth: Option<&str>,
    frequency_penalty: f64,
    max_tokens: u32,
    schema: Option<(&str, serde_json::Value)>,
) -> anyhow::Result<String> {
    let client = reqwest::Client::builder()
        .timeout(std::time::Duration::from_secs(120))
        .build()?;

    let response_format = schema.map(|(name, schema)| ChatResponseFormat {
        kind: "json_schema".to_owned(),
        json_schema: JsonSchemaWrapper { name: name.to_owned(), strict: true, schema },
    });

    let request = ChatRequest {
        model: model.to_owned(),
        messages: vec![
            ChatMessage {
                role: "system".to_owned(),
                content: system_prompt.to_owned(),
            },
            ChatMessage {
                role: "user".to_owned(),
                content: user_message.to_owned(),
            },
        ],
        response_format,
        stream: false,
        temperature: 0.1,
        max_tokens,
        frequency_penalty,
    };

    let url = format!("{}/v1/chat/completions", base_url.trim_end_matches('/'));
    tracing::info!(%url, model, prompt_len = user_message.len(), "Calling LLM API...");

    let start = std::time::Instant::now();
    let mut req = client.post(&url).json(&request);
    if let Some(auth_header) = auth {
        req = req.header("Authorization", auth_header);
    }
    let resp = req.send().await?;
    let elapsed = start.elapsed();

    if !resp.status().is_success() {
        let status = resp.status();
        let body = resp.text().await.unwrap_or_default();
        tracing::error!(%status, body = &body[..body.len().min(500)], "LLM API error");
        anyhow::bail!("LLM returned {}: {}", status, body);
    }

    let chat_resp: ChatResponse = resp.json().await?;
    let content = chat_resp
        .choices
        .into_iter()
        .next()
        .ok_or_else(|| anyhow::anyhow!("LLM returned empty choices"))?
        .message
        .content;
    tracing::info!(
        elapsed_ms = elapsed.as_millis() as u64,
        response_len = content.len(),
        "LLM response received"
    );
    tracing::debug!(raw_response = %content, "LLM raw output");
    Ok(content)
}

fn normalize_schema() -> serde_json::Value {
    serde_json::json!({
        "type": "object",
        "properties": {
            "artist":           { "type": ["string", "null"] },
            "album":            { "type": ["string", "null"] },
            "title":            { "type": ["string", "null"] },
            "year":             { "type": ["integer", "null"] },
            "track_number":     { "type": ["integer", "null"] },
            "genre":            { "type": ["string", "null"] },
            "featured_artists": { "type": "array", "items": { "type": "string" } },
            "release_kind":     { "type": ["string", "null"] },
            "confidence":       { "type": ["number", "null"] },
            "notes":            { "type": ["string", "null"] }
        },
        "required": ["artist", "album", "title", "year", "track_number", "genre", "featured_artists", "release_kind", "confidence", "notes"],
        "additionalProperties": false
    })
}

/// Parse the LLM JSON response into NormalizedFields.
/// Handles both clean JSON and JSON wrapped in markdown code fences.
fn parse_response(response: &str) -> anyhow::Result<NormalizedFields> {
    let cleaned = response.trim();

    // Strip markdown code fences if present
    let json_str = if cleaned.starts_with("```") {
        let start = cleaned.find('{').unwrap_or(0);
        let end = cleaned.rfind('}').map(|i| i + 1).unwrap_or(cleaned.len());
        &cleaned[start..end]
    } else {
        cleaned
    };

    #[derive(Deserialize)]
    struct LlmOutput {
        artist: Option<String>,
        album: Option<String>,
        title: Option<String>,
        year: Option<i32>,
        track_number: Option<i32>,
        genre: Option<String>,
        #[serde(default)]
        featured_artists: Vec<String>,
        #[serde(rename = "release_kind")]
        release_type: Option<String>,
        confidence: Option<f64>,
        notes: Option<String>,
    }

    let parsed: LlmOutput = serde_json::from_str(json_str)
        .map_err(|e| anyhow::anyhow!("Failed to parse LLM response as JSON: {} — raw: {}", e, response))?;

    Ok(NormalizedFields {
        title: parsed.title,
        artist: parsed.artist,
        album: parsed.album,
        year: parsed.year,
        track_number: parsed.track_number,
        genre: parsed.genre,
        featured_artists: parsed.featured_artists,
        release_type: parsed.release_type,
        confidence: parsed.confidence,
        notes: parsed.notes,
    })
}