use console::style;
use indicatif::{ProgressBar, ProgressStyle};
use serde::Serialize;
use std::sync::Arc;
use std::sync::atomic::{AtomicBool, Ordering};
use tracing::Instrument;
use tracing::{info, warn};

use crate::Config;
use crate::core::error::Result;
use crate::core::metrics::{MetricsLayer, StageTiming};

use super::embed::run_embed;
use super::generate_docs::run_generate_docs;
use super::ingest::{IngestDisplay, run_ingest};

#[derive(Debug, Default)]
pub struct SyncOptions {
    pub full: bool,
    pub force: bool,
    pub no_embed: bool,
    pub no_docs: bool,
    pub no_events: bool,
    pub robot_mode: bool,
}

#[derive(Debug, Default, Serialize)]
pub struct SyncResult {
    #[serde(skip)]
    pub run_id: String,
    pub issues_updated: usize,
    pub mrs_updated: usize,
    pub discussions_fetched: usize,
    pub resource_events_fetched: usize,
    pub resource_events_failed: usize,
    pub documents_regenerated: usize,
    pub documents_embedded: usize,
}

fn stage_spinner(stage: u8, total: u8, msg: &str, robot_mode: bool) -> ProgressBar {
    if robot_mode {
        return ProgressBar::hidden();
    }
    let pb = crate::cli::progress::multi().add(ProgressBar::new_spinner());
    pb.set_style(
        ProgressStyle::default_spinner()
            .template("{spinner:.blue} {prefix} {msg}")
            .expect("valid template"),
    );
    pb.enable_steady_tick(std::time::Duration::from_millis(80));
    pb.set_prefix(format!("[{stage}/{total}]"));
    pb.set_message(msg.to_string());
    pb
}

pub async fn run_sync(
    config: &Config,
    options: SyncOptions,
    run_id: Option<&str>,
) -> Result<SyncResult> {
    let generated_id;
    let run_id = match run_id {
        Some(id) => id,
        None => {
            generated_id = uuid::Uuid::new_v4().simple().to_string();
            &generated_id[..8]
        }
    };
    let span = tracing::info_span!("sync", %run_id);

    async move {
        let mut result = SyncResult {
            run_id: run_id.to_string(),
            ..SyncResult::default()
        };

        let ingest_display = if options.robot_mode {
            IngestDisplay::silent()
        } else {
            IngestDisplay::progress_only()
        };

        let total_stages: u8 = if options.no_docs && options.no_embed {
            2
        } else if options.no_docs || options.no_embed {
            3
        } else {
            4
        };
        let mut current_stage: u8 = 0;

        current_stage += 1;
        let spinner = stage_spinner(
            current_stage,
            total_stages,
            "Fetching issues from GitLab...",
            options.robot_mode,
        );
        info!("Sync stage {current_stage}/{total_stages}: ingesting issues");
        let issues_result = run_ingest(
            config,
            "issues",
            None,
            options.force,
            options.full,
            ingest_display,
            Some(spinner.clone()),
        )
        .await?;
        result.issues_updated = issues_result.issues_upserted;
        result.discussions_fetched += issues_result.discussions_fetched;
        result.resource_events_fetched += issues_result.resource_events_fetched;
        result.resource_events_failed += issues_result.resource_events_failed;
        spinner.finish_and_clear();

        current_stage += 1;
        let spinner = stage_spinner(
            current_stage,
            total_stages,
            "Fetching merge requests from GitLab...",
            options.robot_mode,
        );
        info!("Sync stage {current_stage}/{total_stages}: ingesting merge requests");
        let mrs_result = run_ingest(
            config,
            "mrs",
            None,
            options.force,
            options.full,
            ingest_display,
            Some(spinner.clone()),
        )
        .await?;
        result.mrs_updated = mrs_result.mrs_upserted;
        result.discussions_fetched += mrs_result.discussions_fetched;
        result.resource_events_fetched += mrs_result.resource_events_fetched;
        result.resource_events_failed += mrs_result.resource_events_failed;
        spinner.finish_and_clear();

        if !options.no_docs {
            current_stage += 1;
            let spinner = stage_spinner(
                current_stage,
                total_stages,
                "Processing documents...",
                options.robot_mode,
            );
            info!("Sync stage {current_stage}/{total_stages}: generating documents");

            let docs_bar = if options.robot_mode {
                ProgressBar::hidden()
            } else {
                let b = crate::cli::progress::multi().add(ProgressBar::new(0));
                b.set_style(
                    ProgressStyle::default_bar()
                        .template(
                            "    {spinner:.blue} Processing documents [{bar:30.cyan/dim}] {pos}/{len}",
                        )
                        .unwrap()
                        .progress_chars("=> "),
                );
                b
            };
            let docs_bar_clone = docs_bar.clone();
            let tick_started = Arc::new(AtomicBool::new(false));
            let tick_started_clone = Arc::clone(&tick_started);
            let docs_cb: Box<dyn Fn(usize, usize)> = Box::new(move |processed, total| {
                if total > 0 {
                    if !tick_started_clone.swap(true, Ordering::Relaxed) {
                        docs_bar_clone.enable_steady_tick(std::time::Duration::from_millis(100));
                    }
                    docs_bar_clone.set_length(total as u64);
                    docs_bar_clone.set_position(processed as u64);
                }
            });
            let docs_result = run_generate_docs(config, false, None, Some(docs_cb))?;
            result.documents_regenerated = docs_result.regenerated;
            docs_bar.finish_and_clear();
            spinner.finish_and_clear();
        } else {
            info!("Sync: skipping document generation (--no-docs)");
        }

        if !options.no_embed {
            current_stage += 1;
            let spinner = stage_spinner(
                current_stage,
                total_stages,
                "Generating embeddings...",
                options.robot_mode,
            );
            info!("Sync stage {current_stage}/{total_stages}: embedding documents");

            let embed_bar = if options.robot_mode {
                ProgressBar::hidden()
            } else {
                let b = crate::cli::progress::multi().add(ProgressBar::new(0));
                b.set_style(
                    ProgressStyle::default_bar()
                        .template(
                            "    {spinner:.blue} Generating embeddings [{bar:30.cyan/dim}] {pos}/{len}",
                        )
                        .unwrap()
                        .progress_chars("=> "),
                );
                b
            };
            let embed_bar_clone = embed_bar.clone();
            let tick_started = Arc::new(AtomicBool::new(false));
            let tick_started_clone = Arc::clone(&tick_started);
            let embed_cb: Box<dyn Fn(usize, usize)> = Box::new(move |processed, total| {
                if total > 0 {
                    if !tick_started_clone.swap(true, Ordering::Relaxed) {
                        embed_bar_clone.enable_steady_tick(std::time::Duration::from_millis(100));
                    }
                    embed_bar_clone.set_length(total as u64);
                    embed_bar_clone.set_position(processed as u64);
                }
            });
            match run_embed(config, options.full, false, Some(embed_cb)).await {
                Ok(embed_result) => {
                    result.documents_embedded = embed_result.embedded;
                    embed_bar.finish_and_clear();
                    spinner.finish_and_clear();
                }
                Err(e) => {
                    embed_bar.finish_and_clear();
                    spinner.finish_and_clear();
                    if !options.robot_mode {
                        eprintln!("  {} Embedding skipped ({})", style("warn").yellow(), e);
                    }
                    warn!(error = %e, "Embedding stage failed (Ollama may be unavailable), continuing");
                }
            }
        } else {
            info!("Sync: skipping embedding (--no-embed)");
        }

        info!(
            issues = result.issues_updated,
            mrs = result.mrs_updated,
            discussions = result.discussions_fetched,
            resource_events = result.resource_events_fetched,
            resource_events_failed = result.resource_events_failed,
            docs = result.documents_regenerated,
            embedded = result.documents_embedded,
            "Sync pipeline complete"
        );

        Ok(result)
    }
    .instrument(span)
    .await
}

pub fn print_sync(
    result: &SyncResult,
    elapsed: std::time::Duration,
    metrics: Option<&MetricsLayer>,
) {
    println!("{} Sync complete:", style("done").green().bold(),);
    println!("  Issues updated:           {}", result.issues_updated);
    println!("  MRs updated:              {}", result.mrs_updated);
    println!(
        "  Discussions fetched:       {}",
        result.discussions_fetched
    );
    if result.resource_events_fetched > 0 || result.resource_events_failed > 0 {
        println!(
            "  Resource events fetched:   {}",
            result.resource_events_fetched
        );
        if result.resource_events_failed > 0 {
            println!(
                "  Resource events failed:    {}",
                result.resource_events_failed
            );
        }
    }
    println!(
        "  Documents regenerated:     {}",
        result.documents_regenerated
    );
    println!("  Documents embedded:        {}", result.documents_embedded);
    println!("  Elapsed: {:.1}s", elapsed.as_secs_f64());

    if let Some(metrics) = metrics {
        let stages = metrics.extract_timings();
        if !stages.is_empty() {
            print_timing_summary(&stages);
        }
    }
}

fn print_timing_summary(stages: &[StageTiming]) {
    println!();
    println!("{}", style("Stage timing:").dim());
    for stage in stages {
        for sub in &stage.sub_stages {
            print_stage_line(sub, 1);
        }
    }
}

fn print_stage_line(stage: &StageTiming, depth: usize) {
    let indent = "  ".repeat(depth);
    let name = if let Some(ref project) = stage.project {
        format!("{} ({})", stage.name, project)
    } else {
        stage.name.clone()
    };
    let pad_width = 30_usize.saturating_sub(indent.len() + name.len());
    let dots = ".".repeat(pad_width.max(2));

    let mut suffix = String::new();
    if stage.items_processed > 0 {
        suffix.push_str(&format!("{} items", stage.items_processed));
    }
    if stage.errors > 0 {
        if !suffix.is_empty() {
            suffix.push_str(", ");
        }
        suffix.push_str(&format!("{} errors", stage.errors));
    }
    if stage.rate_limit_hits > 0 {
        if !suffix.is_empty() {
            suffix.push_str(", ");
        }
        suffix.push_str(&format!("{} rate limits", stage.rate_limit_hits));
    }

    let time_str = format!("{:.1}s", stage.elapsed_ms as f64 / 1000.0);
    if suffix.is_empty() {
        println!("{indent}{name} {dots} {time_str}");
    } else {
        println!("{indent}{name} {dots} {time_str} ({suffix})");
    }

    for sub in &stage.sub_stages {
        print_stage_line(sub, depth + 1);
    }
}

#[derive(Serialize)]
struct SyncJsonOutput<'a> {
    ok: bool,
    data: &'a SyncResult,
    meta: SyncMeta,
}

#[derive(Serialize)]
struct SyncMeta {
    run_id: String,
    elapsed_ms: u64,
    #[serde(skip_serializing_if = "Vec::is_empty")]
    stages: Vec<StageTiming>,
}

pub fn print_sync_json(result: &SyncResult, elapsed_ms: u64, metrics: Option<&MetricsLayer>) {
    let stages = metrics.map_or_else(Vec::new, MetricsLayer::extract_timings);
    let output = SyncJsonOutput {
        ok: true,
        data: result,
        meta: SyncMeta {
            run_id: result.run_id.clone(),
            elapsed_ms,
            stages,
        },
    };
    println!("{}", serde_json::to_string(&output).unwrap());
}