// Transkripsjons-pipeline — faster-whisper integrasjon.
//
// Henter lydfil fra CAS, sender til faster-whisper HTTP API (SRT-format),
// parser SRT og skriver segmenter til transcription_segments-tabellen.
// Universell tjeneste for all lyd: podcast, møter, voice memos.
//
// Ref: docs/concepts/podcastfabrikken.md

use sqlx::PgPool;
use uuid::Uuid;

use crate::cas::CasStore;
use crate::jobs::JobRow;
use crate::resource_usage;
use crate::stdb::StdbClient;

/// Et parset SRT-segment.
#[derive(Debug)]
struct SrtSegment {
    seq: i32,
    start_ms: i32,
    end_ms: i32,
    content: String,
}

/// Handler for whisper_transcribe-jobber.
///
/// Payload forventer:
///   - media_node_id: UUID — noden som skal oppdateres
///   - cas_hash: String — CAS-nøkkel til lydfilen
///   - mime: String — MIME-type (brukes for filnavn-hint)
///   - language: String (valgfritt, default "no")
///   - initial_prompt: String (valgfritt — navneliste for bedre egennavn)
pub async fn handle_whisper_job(
    job: &JobRow,
    db: &PgPool,
    stdb: &StdbClient,
    cas: &CasStore,
    whisper_url: &str,
) -> Result<serde_json::Value, String> {
    let media_node_id: Uuid = job.payload["media_node_id"]
        .as_str()
        .ok_or("Mangler media_node_id i payload")?
        .parse()
        .map_err(|e| format!("Ugyldig media_node_id: {e}"))?;

    let cas_hash = job.payload["cas_hash"]
        .as_str()
        .ok_or("Mangler cas_hash i payload")?;

    let mime = job.payload["mime"]
        .as_str()
        .unwrap_or("audio/mpeg");

    let language = job.payload["language"]
        .as_str()
        .unwrap_or("no");

    // Hent initial_prompt: payload > miljøvariabel > ingen
    let initial_prompt = match job.payload["initial_prompt"].as_str() {
        Some(p) => Some(p.to_string()),
        None => std::env::var("WHISPER_INITIAL_PROMPT").ok(),
    };

    // Modell: sentral serverinnstilling
    let model = std::env::var("WHISPER_MODEL")
        .unwrap_or_else(|_| "medium".to_string());

    // 1. Les lydfil fra CAS
    let file_path = cas.path_for(cas_hash);
    let file_data = tokio::fs::read(&file_path)
        .await
        .map_err(|e| format!("Kunne ikke lese CAS-fil {cas_hash}: {e}"))?;

    tracing::info!(
        media_node_id = %media_node_id,
        cas_hash = %cas_hash,
        size = file_data.len(),
        model = %model,
        "Sender lydfil til Whisper"
    );

    // 2. Send til faster-whisper API (SRT-format)
    let file_ext = mime_to_extension(mime);
    let file_name = format!("audio.{file_ext}");

    let file_part = reqwest::multipart::Part::bytes(file_data)
        .file_name(file_name)
        .mime_str(mime)
        .map_err(|e| format!("Kunne ikke bygge multipart: {e}"))?;

    let mut form = reqwest::multipart::Form::new()
        .part("file", file_part)
        .text("model", model.clone())
        .text("language", language.to_string())
        .text("response_format", "srt");

    if let Some(ref prompt) = initial_prompt {
        form = form.text("initial_prompt", prompt.clone());
    }

    let client = reqwest::Client::new();
    let url = format!("{whisper_url}/v1/audio/transcriptions");

    let response = client
        .post(&url)
        .multipart(form)
        .timeout(std::time::Duration::from_secs(600)) // 10 min timeout for lange filer
        .send()
        .await
        .map_err(|e| format!("HTTP-feil mot Whisper: {e}"))?;

    if !response.status().is_success() {
        let status = response.status();
        let body = response.text().await.unwrap_or_default();
        return Err(format!("Whisper returnerte {status}: {body}"));
    }

    let srt_text = response
        .text()
        .await
        .map_err(|e| format!("Kunne ikke lese Whisper-respons: {e}"))?;

    // 3. Parse SRT til segmenter
    let segments = parse_srt(&srt_text)?;

    tracing::info!(
        media_node_id = %media_node_id,
        segments = segments.len(),
        "SRT parset"
    );

    if segments.is_empty() {
        return Err("Whisper returnerte tom SRT — ingen segmenter".to_string());
    }

    // 4. Skriv segmenter til transcription_segments-tabellen
    let transcribed_at = chrono::Utc::now();
    insert_segments(db, media_node_id, transcribed_at, &segments).await?;

    // 5. Bygg sammenhengende tekst og oppdater node
    let transcript_text: String = segments
        .iter()
        .map(|s| s.content.trim())
        .collect::<Vec<_>>()
        .join(" ");

    let duration_ms = segments.last().map(|s| s.end_ms).unwrap_or(0);

    update_node_with_transcript(
        db,
        stdb,
        media_node_id,
        &transcript_text,
        transcribed_at,
        segments.len(),
        duration_ms,
    )
    .await?;

    // Logg ressursforbruk (Whisper)
    let triggered_by: Option<Uuid> = job.payload["requested_by"]
        .as_str()
        .and_then(|s| s.parse().ok());
    let collection_id = resource_usage::find_collection_for_node(db, media_node_id).await;
    let duration_seconds = (duration_ms as f64) / 1000.0;

    if let Err(e) = resource_usage::log(
        db,
        media_node_id,
        triggered_by,
        collection_id,
        "whisper",
        serde_json::json!({
            "model": model,
            "duration_seconds": duration_seconds,
            "language": language,
            "mode": "batch"
        }),
    )
    .await
    {
        tracing::warn!(error = %e, "Kunne ikke logge Whisper-ressursforbruk");
    }

    Ok(serde_json::json!({
        "segments": segments.len(),
        "transcript_length": transcript_text.len(),
        "duration_ms": duration_ms,
        "model": model,
        "transcribed_at": transcribed_at.to_rfc3339(),
    }))
}

/// Parser SRT-tekst til en liste med segmenter.
///
/// SRT-format:
/// ```text
/// 1
/// 00:00:00,000 --> 00:00:05,230
/// Hei og velkommen til Sidelinja.
///
/// 2
/// 00:00:05,230 --> 00:00:10,500
/// I dag snakker vi om...
/// ```
fn parse_srt(srt: &str) -> Result<Vec<SrtSegment>, String> {
    let mut segments = Vec::new();
    let mut lines = srt.lines().peekable();

    while lines.peek().is_some() {
        // Hopp over tomme linjer
        while lines.peek().map_or(false, |l| l.trim().is_empty()) {
            lines.next();
        }

        // Sekvensnummer
        let seq_line = match lines.next() {
            Some(l) if !l.trim().is_empty() => l.trim().to_string(),
            _ => break,
        };
        let seq: i32 = seq_line
            .parse()
            .map_err(|_| format!("Ugyldig SRT-sekvensnummer: '{seq_line}'"))?;

        // Tidslinje: 00:00:00,000 --> 00:00:05,230
        let time_line = lines
            .next()
            .ok_or_else(|| format!("Mangler tidslinje etter sekvens {seq}"))?;
        let (start_ms, end_ms) = parse_srt_time_line(time_line)
            .map_err(|e| format!("Ugyldig tidslinje for sekvens {seq}: {e}"))?;

        // Tekstlinjer (frem til tom linje eller slutt)
        let mut text_parts = Vec::new();
        while lines.peek().map_or(false, |l| !l.trim().is_empty()) {
            text_parts.push(lines.next().unwrap().to_string());
        }
        let content = text_parts.join("\n");

        if !content.is_empty() {
            segments.push(SrtSegment {
                seq,
                start_ms,
                end_ms,
                content,
            });
        }
    }

    Ok(segments)
}

/// Parser en SRT-tidslinje: "00:01:23,456 --> 00:01:30,789"
/// Returnerer (start_ms, end_ms).
fn parse_srt_time_line(line: &str) -> Result<(i32, i32), String> {
    let parts: Vec<&str> = line.split("-->").collect();
    if parts.len() != 2 {
        return Err(format!("Forventet 'start --> end', fikk: '{line}'"));
    }
    let start = parse_srt_timestamp(parts[0].trim())?;
    let end = parse_srt_timestamp(parts[1].trim())?;
    Ok((start, end))
}

/// Parser et SRT-tidsstempel: "00:01:23,456" → millisekunder.
fn parse_srt_timestamp(ts: &str) -> Result<i32, String> {
    // Format: HH:MM:SS,mmm
    let ts = ts.replace(',', ".");
    let parts: Vec<&str> = ts.split(':').collect();
    if parts.len() != 3 {
        return Err(format!("Ugyldig tidsstempel: '{ts}'"));
    }
    let hours: f64 = parts[0].parse().map_err(|_| format!("Ugyldig timer: '{}'", parts[0]))?;
    let minutes: f64 = parts[1].parse().map_err(|_| format!("Ugyldig minutter: '{}'", parts[1]))?;
    let seconds: f64 = parts[2].parse().map_err(|_| format!("Ugyldig sekunder: '{}'", parts[2]))?;

    Ok(((hours * 3_600.0 + minutes * 60.0 + seconds) * 1000.0) as i32)
}

/// Setter inn segmenter i transcription_segments-tabellen.
async fn insert_segments(
    db: &PgPool,
    node_id: Uuid,
    transcribed_at: chrono::DateTime<chrono::Utc>,
    segments: &[SrtSegment],
) -> Result<(), String> {
    let mut tx = db.begin().await.map_err(|e| format!("Transaksjon feilet: {e}"))?;

    for seg in segments {
        sqlx::query(
            r#"
            INSERT INTO transcription_segments (node_id, transcribed_at, seq, start_ms, end_ms, content)
            VALUES ($1, $2, $3, $4, $5, $6)
            "#,
        )
        .bind(node_id)
        .bind(transcribed_at)
        .bind(seg.seq)
        .bind(seg.start_ms)
        .bind(seg.end_ms)
        .bind(&seg.content)
        .execute(&mut *tx)
        .await
        .map_err(|e| format!("Kunne ikke sette inn segment {}: {e}", seg.seq))?;
    }

    tx.commit().await.map_err(|e| format!("Commit feilet: {e}"))?;

    tracing::info!(
        node_id = %node_id,
        segments = segments.len(),
        transcribed_at = %transcribed_at,
        "Segmenter skrevet til transcription_segments"
    );

    Ok(())
}

/// Oppdaterer nodens content-felt med sammenhengende tekst og
/// lagrer transkripsjonsmetadata.
async fn update_node_with_transcript(
    db: &PgPool,
    stdb: &StdbClient,
    node_id: Uuid,
    transcript: &str,
    transcribed_at: chrono::DateTime<chrono::Utc>,
    segment_count: usize,
    duration_ms: i32,
) -> Result<(), String> {
    // Hent eksisterende node fra PG for å merge metadata
    let existing = sqlx::query_as::<_, NodeMetadataRow>(
        "SELECT metadata, node_kind, title, visibility::text as visibility FROM nodes WHERE id = $1",
    )
    .bind(node_id)
    .fetch_optional(db)
    .await
    .map_err(|e| format!("PG-feil ved henting av node: {e}"))?
    .ok_or_else(|| format!("Node {node_id} finnes ikke"))?;

    // Merge transcription-data inn i eksisterende metadata
    let mut metadata = existing.metadata.clone();
    metadata["transcription"] = serde_json::json!({
        "duration_ms": duration_ms,
        "segment_count": segment_count,
        "transcribed_at": transcribed_at.to_rfc3339(),
    });

    let metadata_str = metadata.to_string();
    let node_id_str = node_id.to_string();
    let title = existing.title.clone().unwrap_or_default();

    // Oppdater STDB (instant feedback) — best-effort, PG er autoritativ
    if let Err(e) = stdb.update_node(
        &node_id_str,
        &existing.node_kind,
        &title,
        transcript,
        &existing.visibility,
        &metadata_str,
    )
    .await
    {
        tracing::warn!(
            node_id = %node_id,
            error = %e,
            "Kunne ikke oppdatere STDB med transkripsjon (fortsetter med PG)"
        );
    }

    // Oppdater PG (persistent)
    sqlx::query(
        r#"
        UPDATE nodes
        SET content = $2, metadata = $3
        WHERE id = $1
        "#,
    )
    .bind(node_id)
    .bind(transcript)
    .bind(&metadata)
    .execute(db)
    .await
    .map_err(|e| format!("PG update feilet: {e}"))?;

    tracing::info!(
        node_id = %node_id,
        transcript_len = transcript.len(),
        "Node oppdatert med transkripsjon"
    );

    Ok(())
}

#[derive(sqlx::FromRow)]
struct NodeMetadataRow {
    metadata: serde_json::Value,
    node_kind: String,
    title: Option<String>,
    visibility: String,
}

/// Konverterer MIME-type til filendelse for Whisper-hinting.
fn mime_to_extension(mime: &str) -> &str {
    match mime {
        "audio/mpeg" | "audio/mp3" => "mp3",
        "audio/wav" | "audio/x-wav" => "wav",
        "audio/ogg" => "ogg",
        "audio/flac" | "audio/x-flac" => "flac",
        "audio/mp4" | "audio/m4a" | "audio/x-m4a" => "m4a",
        "audio/webm" => "webm",
        _ => "wav",
    }
}

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

    #[test]
    fn test_parse_srt_timestamp() {
        assert_eq!(parse_srt_timestamp("00:00:00,000").unwrap(), 0);
        assert_eq!(parse_srt_timestamp("00:01:23,456").unwrap(), 83456);
        assert_eq!(parse_srt_timestamp("01:00:00,000").unwrap(), 3_600_000);
        assert_eq!(parse_srt_timestamp("00:00:05,230").unwrap(), 5230);
    }

    #[test]
    fn test_parse_srt() {
        let srt = "\
1
00:00:00,000 --> 00:00:05,230
Hei og velkommen til Sidelinja.

2
00:00:05,230 --> 00:00:10,500
I dag snakker vi om fotball.
";
        let segments = parse_srt(srt).unwrap();
        assert_eq!(segments.len(), 2);
        assert_eq!(segments[0].seq, 1);
        assert_eq!(segments[0].start_ms, 0);
        assert_eq!(segments[0].end_ms, 5230);
        assert_eq!(segments[0].content, "Hei og velkommen til Sidelinja.");
        assert_eq!(segments[1].seq, 2);
        assert_eq!(segments[1].start_ms, 5230);
        assert_eq!(segments[1].end_ms, 10500);
    }

    #[test]
    fn test_parse_srt_time_line() {
        let (start, end) = parse_srt_time_line("00:01:23,456 --> 00:01:30,789").unwrap();
        assert_eq!(start, 83456);
        assert_eq!(end, 90789);
    }

    #[test]
    fn test_parse_srt_empty() {
        let segments = parse_srt("").unwrap();
        assert!(segments.is_empty());
    }
}