// synops-prune — Opprydding av gamle CAS-filer basert på TTL og diskbruk.
//
// Tre-fase pruning:
//   Fase 1 (disk ≥ 85%): Slett generert innhold (TTS, thumbnails — regenererbart)
//   Fase 2 (alltid):      TTL-basert pruning per modalitet (lyd 30d, bilde 30d, video 14d)
//   Fase 3 (disk ≥ 95%):  Kritisk — alt uten publishing-edge slettes (tekst beholdes)
//
// Signaler som forlenger levetid:
//   - Publishing-edge → behold for alltid (unntatt kritisk)
//   - last_accessed_at innenfor TTL → forleng
//   - Utranskribert lyd → behold i normal modus
//
// Input:
//   --dry-run        Forhåndsvisning uten sletting (default)
//   --write          Faktisk slett filer
//   --cas-root PATH  CAS-katalog (default: /srv/synops/media/cas)
//   --audio-ttl N    TTL for lyd i dager (default: 30)
//   --image-ttl N    TTL for bilder i dager (default: 30)
//   --video-ttl N    TTL for video i dager (default: 14)
//
// Miljøvariabler:
//   DATABASE_URL — PostgreSQL-tilkobling (påkrevd)
//   CAS_ROOT     — Alternativ til --cas-root
//
// Erstatter: maskinrommet/src/pruning.rs
// Ref: docs/retninger/unix_filosofi.md

use chrono::{DateTime, Utc};
use clap::Parser;
use serde::Serialize;
use std::path::{Path, PathBuf};
use std::process;
use uuid::Uuid;

/// Opprydding av gamle CAS-filer basert på TTL og diskbruk.
#[derive(Parser)]
#[command(name = "synops-prune", about = "Rydd opp gamle CAS-filer (TTL + disk-nødventil)")]
struct Cli {
    /// Forhåndsvisning — vis hva som ville blitt slettet uten å slette
    #[arg(long, default_value_t = false)]
    dry_run: bool,

    /// Faktisk slett filer (uten dette flagget er dry-run implisitt)
    #[arg(long, default_value_t = false)]
    write: bool,

    /// CAS-rotkatalog
    #[arg(long, env = "CAS_ROOT", default_value = "/srv/synops/media/cas")]
    cas_root: PathBuf,

    /// TTL for lydfiler i dager
    #[arg(long, default_value_t = 30)]
    audio_ttl: i64,

    /// TTL for bilder i dager
    #[arg(long, default_value_t = 30)]
    image_ttl: i64,

    /// TTL for video i dager
    #[arg(long, default_value_t = 14)]
    video_ttl: i64,
}

impl Cli {
    /// Effektiv dry-run: sant hvis --dry-run er satt ELLER --write ikke er satt.
    fn is_dry_run(&self) -> bool {
        self.dry_run || !self.write
    }
}

// --- Datastrukturer ---

#[derive(Debug, sqlx::FromRow)]
struct PruneCandidate {
    id: Uuid,
    cas_hash: String,
    mime_category: String,
    size_bytes: i64,
    created_at: DateTime<Utc>,
    last_accessed_at: Option<DateTime<Utc>>,
    has_publishing_edge: bool,
    is_generated: bool,
    has_transcription: bool,
}

#[derive(Debug, Default, Serialize)]
struct PhaseResult {
    checked: usize,
    would_delete: usize,
    deleted: usize,
    bytes_freed: u64,
}

#[derive(Debug, Serialize)]
struct PruneOutput {
    status: &'static str,
    dry_run: bool,
    candidates_checked: usize,
    files_deleted: usize,
    bytes_freed: u64,
    disk_pct_before: f64,
    disk_pct_after: f64,
    emergency_level: &'static str,
    phases: PrunePhases,
}

#[derive(Debug, Serialize)]
struct PrunePhases {
    generated: PhaseResult,
    ttl: PhaseResult,
    critical: PhaseResult,
}

// --- CAS-operasjoner ---

/// Sjekk diskbruk-prosent for partisjonen CAS-katalogen ligger på.
async fn disk_usage_percent(cas_root: &Path) -> Result<f64, String> {
    let output = tokio::process::Command::new("df")
        .args(["--output=pcent", cas_root.to_str().unwrap_or("/")])
        .output()
        .await
        .map_err(|e| format!("df-kommando feilet: {e}"))?;
    if !output.status.success() {
        return Err("df-kommando returnerte feil".into());
    }
    let stdout = String::from_utf8_lossy(&output.stdout);
    let pct: f64 = stdout
        .lines()
        .nth(1)
        .and_then(|line| line.trim().trim_end_matches('%').parse().ok())
        .unwrap_or(0.0);
    Ok(pct)
}

/// Beregn filsti for en CAS-hash (2-tegn prefix-katalog).
fn cas_path_for(cas_root: &Path, hash: &str) -> PathBuf {
    let prefix = &hash[..2.min(hash.len())];
    cas_root.join(prefix).join(hash)
}

/// Slett en CAS-fil. Returnerer bytes frigitt (0 hvis filen ikke fantes).
async fn cas_delete(cas_root: &Path, hash: &str) -> Result<u64, String> {
    let path = cas_path_for(cas_root, hash);
    match tokio::fs::metadata(&path).await {
        Ok(meta) => {
            let size = meta.len();
            tokio::fs::remove_file(&path)
                .await
                .map_err(|e| format!("Kunne ikke slette {}: {e}", path.display()))?;
            Ok(size)
        }
        Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(0),
        Err(e) => Err(format!("Kunne ikke lese metadata for {}: {e}", path.display())),
    }
}

/// Sjekk om en CAS-fil eksisterer og returner størrelse.
async fn cas_file_size(cas_root: &Path, hash: &str) -> u64 {
    let path = cas_path_for(cas_root, hash);
    tokio::fs::metadata(&path)
        .await
        .map(|m| m.len())
        .unwrap_or(0)
}

// --- Logg ---

async fn log_prune(db: &sqlx::PgPool, node_id: Uuid, hash: &str, bytes: u64, reason: &str) {
    let detail = serde_json::json!({
        "hash": hash,
        "size_bytes": bytes,
        "operation": "delete",
        "reason": reason,
    });
    let _ = sqlx::query(
        "INSERT INTO resource_usage_log (target_node_id, resource_type, detail) VALUES ($1, 'cas', $2)",
    )
    .bind(node_id)
    .bind(&detail)
    .execute(db)
    .await
    .map_err(|e| tracing::warn!(error = %e, "Kunne ikke logge pruning-hendelse"));
}

// --- Fasene ---

/// Fase 1: Slett generert innhold (TTS, thumbnails) — kan regenereres.
async fn phase_generated(
    db: &sqlx::PgPool,
    cas_root: &Path,
    dry_run: bool,
) -> Result<PhaseResult, String> {
    let rows: Vec<(String, Uuid)> = sqlx::query_as(
        r#"
        SELECT metadata->>'cas_hash' AS cas_hash, id
        FROM nodes
        WHERE node_kind = 'media'
          AND metadata->>'cas_hash' IS NOT NULL
          AND (
            metadata ? 'tts'
            OR metadata->>'generated' = 'true'
          )
        "#,
    )
    .fetch_all(db)
    .await
    .map_err(|e| format!("Spørring for generert innhold feilet: {e}"))?;

    let mut result = PhaseResult {
        checked: rows.len(),
        ..Default::default()
    };

    for (hash, node_id) in &rows {
        let size = cas_file_size(cas_root, hash).await;
        if size == 0 {
            continue; // Allerede borte
        }

        result.would_delete += 1;

        if dry_run {
            result.bytes_freed += size;
            tracing::info!(hash = %hash, node_id = %node_id, size, "Fase 1: ville slettet generert fil");
        } else {
            match cas_delete(cas_root, hash).await {
                Ok(bytes) if bytes > 0 => {
                    result.deleted += 1;
                    result.bytes_freed += bytes;
                    log_prune(db, *node_id, hash, bytes, "generated_cleanup").await;
                }
                Ok(_) => {}
                Err(e) => tracing::warn!(hash = %hash, error = %e, "Kunne ikke slette generert fil"),
            }
        }
    }

    Ok(result)
}

/// Fase 2: TTL-basert pruning per modalitet.
async fn phase_ttl(
    db: &sqlx::PgPool,
    cas_root: &Path,
    audio_ttl: i64,
    image_ttl: i64,
    video_ttl: i64,
    emergency_level: &str,
    dry_run: bool,
) -> Result<PhaseResult, String> {
    let candidates: Vec<PruneCandidate> = sqlx::query_as(
        r#"
        SELECT
            n.id,
            n.metadata->>'cas_hash' AS cas_hash,
            CASE
                WHEN n.metadata->>'mime' LIKE 'audio/%' THEN 'audio'
                WHEN n.metadata->>'mime' LIKE 'image/%' THEN 'image'
                WHEN n.metadata->>'mime' LIKE 'video/%' THEN 'video'
                ELSE 'other'
            END AS mime_category,
            COALESCE((n.metadata->>'size_bytes')::bigint, 0) AS size_bytes,
            n.created_at,
            n.last_accessed_at,
            EXISTS(
                SELECT 1 FROM edges e
                WHERE (e.source_id = n.id OR e.target_id = n.id)
                  AND e.edge_type IN ('belongs_to', 'has_media')
                  AND EXISTS(
                    SELECT 1 FROM edges pub
                    WHERE pub.edge_type = 'publishing'
                      AND (pub.source_id = e.target_id OR pub.source_id = e.source_id)
                  )
            ) AS has_publishing_edge,
            COALESCE(n.metadata ? 'tts' OR n.metadata->>'generated' = 'true', false) AS is_generated,
            EXISTS(
                SELECT 1 FROM transcription_segments ts
                WHERE ts.node_id = n.id
            ) AS has_transcription
        FROM nodes n
        WHERE n.node_kind = 'media'
          AND n.metadata->>'cas_hash' IS NOT NULL
        ORDER BY n.created_at ASC
        "#,
    )
    .fetch_all(db)
    .await
    .map_err(|e| format!("TTL-kandidatspørring feilet: {e}"))?;

    let now = Utc::now();
    let mut result = PhaseResult {
        checked: candidates.len(),
        ..Default::default()
    };

    for c in &candidates {
        // Tekst/transkripsjon slettes aldri
        if c.mime_category == "other" {
            continue;
        }

        // Publishing-edge = behold for alltid (unntatt ved kritisk)
        if c.has_publishing_edge && emergency_level != "critical" {
            continue;
        }

        // Bestem TTL basert på modalitet og nødsituasjon
        let ttl_days = match emergency_level {
            "critical" => 0,
            "aggressive" => match c.mime_category.as_str() {
                "audio" => audio_ttl / 3,
                "image" => image_ttl / 3,
                "video" => 1,
                _ => i64::MAX,
            },
            _ => match c.mime_category.as_str() {
                "audio" => audio_ttl,
                "image" => image_ttl,
                "video" => video_ttl,
                _ => i64::MAX,
            },
        };

        if ttl_days == i64::MAX {
            continue;
        }

        // Beregn effektiv alder — siste tilgang forlenger levetiden
        let reference_time = c.last_accessed_at.unwrap_or(c.created_at);
        let age_days = (now - reference_time).num_days();

        if age_days < ttl_days {
            continue;
        }

        // Lyd uten transkripsjon: behold lengre (trenger transkribering først)
        if c.mime_category == "audio" && !c.has_transcription && emergency_level == "normal" {
            tracing::debug!(node_id = %c.id, "Beholder utranskribert lyd");
            continue;
        }

        // Allerede håndtert generert innhold i fase 1
        if c.is_generated {
            continue;
        }

        let size = if c.size_bytes > 0 {
            c.size_bytes as u64
        } else {
            cas_file_size(cas_root, &c.cas_hash).await
        };

        if size == 0 {
            continue;
        }

        result.would_delete += 1;

        if dry_run {
            result.bytes_freed += size;
            tracing::info!(
                hash = %c.cas_hash,
                node_id = %c.id,
                mime = %c.mime_category,
                age_days,
                ttl_days,
                size,
                "Fase 2: ville slettet TTL-utløpt fil"
            );
        } else {
            match cas_delete(cas_root, &c.cas_hash).await {
                Ok(bytes) if bytes > 0 => {
                    result.deleted += 1;
                    result.bytes_freed += bytes;
                    log_prune(db, c.id, &c.cas_hash, bytes, "ttl_expired").await;
                }
                Ok(_) => {}
                Err(e) => tracing::warn!(hash = %c.cas_hash, error = %e, "Kunne ikke slette CAS-fil"),
            }
        }
    }

    Ok(result)
}

/// Fase 3: Kritisk — slett ALT uten publishing-edge (unntatt tekst).
async fn phase_critical(
    db: &sqlx::PgPool,
    cas_root: &Path,
    dry_run: bool,
) -> Result<PhaseResult, String> {
    let rows: Vec<(String, Uuid, i64)> = sqlx::query_as(
        r#"
        SELECT
            n.metadata->>'cas_hash' AS cas_hash,
            n.id,
            COALESCE((n.metadata->>'size_bytes')::bigint, 0) AS size_bytes
        FROM nodes n
        WHERE n.node_kind = 'media'
          AND n.metadata->>'cas_hash' IS NOT NULL
          AND NOT EXISTS(
            SELECT 1 FROM edges e
            WHERE (e.source_id = n.id OR e.target_id = n.id)
              AND e.edge_type IN ('belongs_to', 'has_media')
              AND EXISTS(
                SELECT 1 FROM edges pub
                WHERE pub.edge_type = 'publishing'
                  AND (pub.source_id = e.target_id OR pub.source_id = e.source_id)
              )
          )
        "#,
    )
    .fetch_all(db)
    .await
    .map_err(|e| format!("Kritisk pruning-spørring feilet: {e}"))?;

    let mut result = PhaseResult {
        checked: rows.len(),
        ..Default::default()
    };

    for (hash, node_id, size_bytes) in &rows {
        let size = if *size_bytes > 0 {
            *size_bytes as u64
        } else {
            cas_file_size(cas_root, hash).await
        };

        if size == 0 {
            continue;
        }

        result.would_delete += 1;

        if dry_run {
            result.bytes_freed += size;
            tracing::info!(hash = %hash, node_id = %node_id, size, "Fase 3: ville slettet (kritisk)");
        } else {
            match cas_delete(cas_root, hash).await {
                Ok(bytes) if bytes > 0 => {
                    result.deleted += 1;
                    result.bytes_freed += bytes;
                    log_prune(db, *node_id, hash, bytes, "critical_emergency").await;
                }
                Ok(_) => {}
                Err(e) => tracing::warn!(hash = %hash, error = %e, "Kritisk: kunne ikke slette CAS-fil"),
            }
        }
    }

    Ok(result)
}

// --- Main ---

#[tokio::main]
async fn main() {
    let cli = Cli::parse();

    synops_common::logging::init("synops_prune");

    let dry_run = cli.is_dry_run();

    if let Err(e) = run(cli, dry_run).await {
        tracing::error!(error = %e, "synops-prune feilet");
        eprintln!("{e}");
        process::exit(1);
    }
}

async fn run(cli: Cli, dry_run: bool) -> Result<(), String> {
    let db = synops_common::db::connect().await?;

    // Sjekk at CAS-katalogen eksisterer
    if !cli.cas_root.exists() {
        return Err(format!("CAS-katalog finnes ikke: {}", cli.cas_root.display()));
    }

    let disk_pct_before = disk_usage_percent(&cli.cas_root).await?;

    let emergency_level = if disk_pct_before >= 95.0 {
        "critical"
    } else if disk_pct_before >= 90.0 {
        "aggressive"
    } else if disk_pct_before >= 85.0 {
        "warning"
    } else {
        "normal"
    };

    tracing::info!(
        disk_pct = disk_pct_before,
        level = emergency_level,
        dry_run,
        "Pruning startet"
    );

    // Fase 1: Slett generert innhold ved disk ≥ 85%
    let generated = if disk_pct_before >= 85.0 {
        phase_generated(&db, &cli.cas_root, dry_run).await?
    } else {
        PhaseResult::default()
    };

    if generated.would_delete > 0 || generated.deleted > 0 {
        tracing::info!(
            would_delete = generated.would_delete,
            deleted = generated.deleted,
            bytes = generated.bytes_freed,
            "Fase 1: Generert innhold"
        );
    }

    // Fase 2: TTL-basert pruning (alltid)
    let ttl = phase_ttl(
        &db,
        &cli.cas_root,
        cli.audio_ttl,
        cli.image_ttl,
        cli.video_ttl,
        emergency_level,
        dry_run,
    )
    .await?;

    if ttl.would_delete > 0 || ttl.deleted > 0 {
        tracing::info!(
            checked = ttl.checked,
            would_delete = ttl.would_delete,
            deleted = ttl.deleted,
            bytes = ttl.bytes_freed,
            "Fase 2: TTL-basert pruning"
        );
    }

    // Fase 3: Kritisk pruning ved disk ≥ 95%
    let critical = if disk_pct_before >= 95.0 {
        phase_critical(&db, &cli.cas_root, dry_run).await?
    } else {
        PhaseResult::default()
    };

    if critical.would_delete > 0 || critical.deleted > 0 {
        tracing::warn!(
            would_delete = critical.would_delete,
            deleted = critical.deleted,
            bytes = critical.bytes_freed,
            "Fase 3: KRITISK pruning"
        );
    }

    // Diskbruk etter pruning
    let disk_pct_after = if !dry_run {
        disk_usage_percent(&cli.cas_root).await.unwrap_or(disk_pct_before)
    } else {
        disk_pct_before // Ingen endring ved dry-run
    };

    let total_deleted = generated.deleted + ttl.deleted + critical.deleted;
    let total_would_delete = generated.would_delete + ttl.would_delete + critical.would_delete;
    let total_bytes = generated.bytes_freed + ttl.bytes_freed + critical.bytes_freed;

    let output = PruneOutput {
        status: if dry_run { "dry_run" } else { "completed" },
        dry_run,
        candidates_checked: generated.checked + ttl.checked + critical.checked,
        files_deleted: if dry_run { total_would_delete } else { total_deleted },
        bytes_freed: total_bytes,
        disk_pct_before,
        disk_pct_after,
        emergency_level,
        phases: PrunePhases {
            generated,
            ttl,
            critical,
        },
    };

    println!(
        "{}",
        serde_json::to_string_pretty(&output).map_err(|e| format!("JSON-serialisering feilet: {e}"))?
    );

    Ok(())
}