use crate::EventRecord;
use anyhow::Result;
use std::collections::{BTreeMap, HashMap};
use std::fs;

/// Obsidian vault projector (deterministic, byte-identical).
pub struct ObsidianProjector {
    vault_dir: String,
    _emit_evidence: bool,
}

/// Vault note metadata (stable frontmatter order).
#[derive(Debug, Clone)]
pub struct VaultNote {
    pub project: String,
    pub level: String,
    pub query_id: Option<String>,
    pub updated: String,
    pub chunks_seen: u32,
    pub chunks_used: u32,
    pub run_id: String,
    pub body: String,
    pub parents: Vec<(String, String)>,
}

impl ObsidianProjector {
    /// Create projector.
    pub fn new(_log_dir: &str, vault_dir: &str, emit_evidence: bool) -> Self {
        Self {
            vault_dir: vault_dir.to_string(),
            _emit_evidence: emit_evidence,
        }
    }

    /// Project log to vault (deterministic).
    pub fn project(&self, events: &[EventRecord]) -> Result<()> {
        fs::create_dir_all(&self.vault_dir)?;

        // Group by project and query
        let mut by_project: HashMap<String, HashMap<String, Vec<&EventRecord>>> = HashMap::new();

        for event in events {
            by_project
                .entry(event.project.clone())
                .or_insert_with(HashMap::new)
                .entry(event.query.clone())
                .or_insert_with(Vec::new)
                .push(event);
        }

        // Generate notes per project (in sorted order for determinism)
        let mut sorted_projects: Vec<_> = by_project.iter().collect();
        sorted_projects.sort_by_key(|(p, _)| p.as_str());

        for (project, queries) in sorted_projects {
            let proj_dir = format!("{}/{}", self.vault_dir, project);
            fs::create_dir_all(&proj_dir)?;

            // Generate index (L2)
            let index_note = VaultNote {
                project: project.clone(),
                level: "L2".to_string(),
                query_id: None,
                updated: "2026-01-01".to_string(),
                chunks_seen: 0,
                chunks_used: 0,
                run_id: "index".to_string(),
                body: String::new(),
                parents: vec![],
            };
            self.write_note(&proj_dir, "index", &index_note)?;

            // Generate per-query notes (L1) in sorted order
            let mut sorted_queries: Vec<_> = queries.iter().collect();
            sorted_queries.sort_by_key(|(qid, _)| qid.as_str());

            for (query_id, query_events) in sorted_queries {
                let (chunks_seen, chunks_used, body, parents) =
                    Self::summarize_query(query_events);

                let note = VaultNote {
                    project: project.clone(),
                    level: "L1".to_string(),
                    query_id: Some(query_id.to_string()),
                    updated: "2026-01-01".to_string(),
                    chunks_seen,
                    chunks_used,
                    run_id: "run1".to_string(),
                    body,
                    parents,
                };

                self.write_note(&proj_dir, query_id, &note)?;
            }
        }

        Ok(())
    }

    /// Write note with deterministic formatting.
    fn write_note(&self, dir: &str, name: &str, note: &VaultNote) -> Result<()> {
        // Stable frontmatter order (BTreeMap keeps keys sorted)
        let mut fm = BTreeMap::new();
        fm.insert("chunks_seen", note.chunks_seen.to_string());
        fm.insert("chunks_used", note.chunks_used.to_string());
        fm.insert("level", note.level.clone());
        fm.insert("project", note.project.clone());
        if let Some(qid) = &note.query_id {
            fm.insert("query_id", qid.clone());
        }
        fm.insert("run_id", note.run_id.clone());
        fm.insert("updated", note.updated.clone());

        // Build frontmatter
        let mut content = String::from("---\n");
        for (k, v) in fm.iter() {
            content.push_str(&format!("{}: {}\n", k, v));
        }
        content.push_str("---\n");

        // Title
        let title = note.query_id.as_ref().unwrap_or(&note.project);
        content.push_str(&format!("# {}\n\n", title));

        // Body
        if note.body.is_empty() {
            content.push_str("No evidence found.\n\n");
        } else {
            content.push_str(&note.body);
            if !note.body.ends_with('\n') {
                content.push('\n');
            }
            content.push('\n');
        }

        // Provenance (sorted)
        if !note.parents.is_empty() {
            content.push_str("## Provenance\n");
            let mut sorted_parents = note.parents.clone();
            sorted_parents.sort();
            for (source, time) in sorted_parents {
                content.push_str(&format!("- [[{}-{}]]\n", source, time));
            }
        }

        // Ensure exactly one trailing newline
        if !content.ends_with('\n') {
            content.push('\n');
        }

        // Write to file
        let path = format!("{}/{}.md", dir, name);
        fs::write(&path, &content)?;

        Ok(())
    }

    /// Summarize query events.
    fn summarize_query(
        events: &[&EventRecord],
    ) -> (u32, u32, String, Vec<(String, String)>) {
        let mut chunks_seen = 0u32;
        let mut chunks_used = 0u32;
        let mut body = String::new();
        let mut parents = Vec::new();

        for event in events.iter() {
            if event.event_type.contains("Gate") {
                chunks_seen += 1;
            }
            if event.event_type.contains("Evidence") {
                chunks_used += 1;
            }
            // Simplified parent extraction
            if let Some(obj) = event.data.as_object() {
                if let Some(parent) = obj.get("parent") {
                    if let Some(s) = parent.as_str() {
                        parents.push((s.to_string(), format!("t{}", event.turn)));
                    }
                }
            }
        }

        if chunks_used > 0 {
            body = format!(
                "Extracted from {} chunks, using {}\n",
                chunks_seen, chunks_used
            );
        }

        (chunks_seen, chunks_used, body, parents)
    }
}