use anyhow::{bail, Context, Result};
use chrono::Utc;
use serde::{Deserialize, Serialize};
use serde_json::{json, Value};
use std::path::{Path, PathBuf};
use uuid::Uuid;

#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct StoredMessage {
    pub role: String,
    pub content: Value,
}

#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct ThreadRecord {
    pub id: String,
    pub title: String,
    pub model: Option<String>,
    pub created_at: String,
    pub updated_at: String,
    pub messages: Vec<StoredMessage>,
}

#[derive(Debug, Clone, Serialize)]
pub struct ThreadSummary {
    pub id: String,
    pub title: String,
    pub model: Option<String>,
    pub created_at: String,
    pub updated_at: String,
    pub message_count: usize,
    pub preview: String,
}

#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct PackedDocument {
    pub name: String,
    pub content: String,
}

pub fn ensure_workspace(root: &Path) -> Result<()> {
    for relative in [
        "workspace/documents",
        "workspace/settings",
        "workspace/threads",
        "workspace/exports",
        "workspace/voice",
        "workspace/scout",
        "logs",
    ] {
        std::fs::create_dir_all(root.join(relative))
            .with_context(|| format!("cannot create {relative}"))?;
    }
    Ok(())
}

pub fn create_thread(
    root: &Path,
    title: Option<&str>,
    model: Option<String>,
) -> Result<ThreadRecord> {
    let now = Utc::now().to_rfc3339();
    let thread = ThreadRecord {
        id: Uuid::new_v4().to_string(),
        title: clean_title(title.unwrap_or("New conversation")),
        model,
        created_at: now.clone(),
        updated_at: now,
        messages: Vec::new(),
    };
    save_thread(root, &thread)?;
    Ok(thread)
}

pub fn list_threads(root: &Path, filter: Option<&str>) -> Result<Vec<ThreadSummary>> {
    let filter = filter.unwrap_or("").trim().to_lowercase();
    let mut summaries = Vec::new();
    let dir = root.join("workspace/threads");
    if !dir.exists() {
        return Ok(summaries);
    }
    for entry in
        std::fs::read_dir(&dir).with_context(|| format!("cannot read {}", dir.display()))?
    {
        let entry = match entry {
            Ok(value) => value,
            Err(_) => continue,
        };
        if !entry.path().is_file()
            || entry.path().extension().and_then(|v| v.to_str()) != Some("json")
        {
            continue;
        }
        let thread: ThreadRecord = match read_json_typed(&entry.path()) {
            Ok(value) => value,
            Err(_) => continue,
        };
        let preview = thread
            .messages
            .iter()
            .rev()
            .find_map(|message| message.content.as_str())
            .unwrap_or("")
            .chars()
            .take(160)
            .collect::<String>();
        if !filter.is_empty()
            && !thread.title.to_lowercase().contains(&filter)
            && !preview.to_lowercase().contains(&filter)
        {
            continue;
        }
        summaries.push(ThreadSummary {
            id: thread.id,
            title: thread.title,
            model: thread.model,
            created_at: thread.created_at,
            updated_at: thread.updated_at,
            message_count: thread.messages.len(),
            preview,
        });
    }
    summaries.sort_by(|a, b| b.updated_at.cmp(&a.updated_at));
    Ok(summaries)
}

pub fn load_thread(root: &Path, id: &str) -> Result<ThreadRecord> {
    validate_thread_id(id)?;
    let path = thread_path(root, id);
    read_json_typed(&path).with_context(|| format!("thread not found: {id}"))
}

pub fn save_thread(root: &Path, thread: &ThreadRecord) -> Result<()> {
    validate_thread_id(&thread.id)?;
    write_json_pretty(&thread_path(root, &thread.id), thread)
}

pub fn rename_thread(root: &Path, id: &str, title: &str) -> Result<ThreadRecord> {
    let mut thread = load_thread(root, id)?;
    thread.title = clean_title(title);
    thread.updated_at = Utc::now().to_rfc3339();
    save_thread(root, &thread)?;
    Ok(thread)
}

pub fn delete_thread(root: &Path, id: &str) -> Result<()> {
    validate_thread_id(id)?;
    let path = thread_path(root, id);
    if path.exists() {
        std::fs::remove_file(&path).with_context(|| format!("cannot delete {}", path.display()))?;
    }
    Ok(())
}

pub fn append_message(thread: &mut ThreadRecord, role: &str, content: Value) {
    thread.messages.push(StoredMessage {
        role: role.to_string(),
        content,
    });
    thread.updated_at = Utc::now().to_rfc3339();
}

pub fn list_documents_with_content(root: &Path) -> Result<Vec<PackedDocument>> {
    let mut documents = Vec::new();
    let dir = root.join("workspace/documents");
    if !dir.exists() {
        return Ok(documents);
    }
    for entry in
        std::fs::read_dir(&dir).with_context(|| format!("cannot read {}", dir.display()))?
    {
        let entry = match entry {
            Ok(value) => value,
            Err(_) => continue,
        };
        if !entry.path().is_file() {
            continue;
        }
        let name = entry.file_name().to_string_lossy().to_string();
        if !safe_filename(&name) {
            continue;
        }
        let content = match std::fs::read_to_string(entry.path()) {
            Ok(value) => value,
            Err(_) => continue,
        };
        documents.push(PackedDocument { name, content });
    }
    documents.sort_by(|a, b| a.name.cmp(&b.name));
    Ok(documents)
}

pub fn save_document(root: &Path, name: &str, content: &str) -> Result<PathBuf> {
    if !safe_filename(name) {
        bail!("unsafe filename");
    }
    let path = root.join("workspace/documents").join(name);
    std::fs::write(&path, content.as_bytes())
        .with_context(|| format!("cannot write {}", path.display()))?;
    Ok(path)
}

pub fn read_settings(root: &Path) -> Value {
    let path = root.join("workspace/settings/settings.json");
    read_json_value(&path).unwrap_or_else(|_| {
        json!({
            "mode": "simple",
            "offline_lock": true,
            "tools_lock": true,
            "phone_access_enabled": false
        })
    })
}

pub fn write_settings(root: &Path, settings: &Value) -> Result<()> {
    write_json_pretty(&root.join("workspace/settings/settings.json"), settings)
}

pub fn read_all_threads(root: &Path) -> Result<Vec<ThreadRecord>> {
    let mut threads = Vec::new();
    for summary in list_threads(root, None)? {
        if let Ok(thread) = load_thread(root, &summary.id) {
            threads.push(thread);
        }
    }
    Ok(threads)
}

pub fn import_threads(root: &Path, threads: &[ThreadRecord], replace: bool) -> Result<usize> {
    let dir = root.join("workspace/threads");
    if replace && dir.exists() {
        for entry in std::fs::read_dir(&dir)? {
            let entry = entry?;
            if entry.path().is_file()
                && entry.path().extension().and_then(|v| v.to_str()) == Some("json")
            {
                std::fs::remove_file(entry.path())?;
            }
        }
    }
    let mut count = 0;
    for thread in threads {
        validate_thread_id(&thread.id)?;
        save_thread(root, thread)?;
        count += 1;
    }
    Ok(count)
}

fn thread_path(root: &Path, id: &str) -> PathBuf {
    root.join("workspace/threads").join(format!("{id}.json"))
}

fn validate_thread_id(id: &str) -> Result<()> {
    Uuid::parse_str(id).with_context(|| "invalid thread id")?;
    Ok(())
}

fn clean_title(title: &str) -> String {
    let cleaned = title
        .trim()
        .chars()
        .filter(|c| !c.is_control())
        .take(120)
        .collect::<String>();
    if cleaned.is_empty() {
        "New conversation".to_string()
    } else {
        cleaned
    }
}

fn safe_filename(name: &str) -> bool {
    !name.is_empty()
        && name.len() <= 120
        && !name.contains("..")
        && !name.contains('/')
        && !name.contains('\\')
        && name
            .chars()
            .all(|c| c.is_ascii_alphanumeric() || matches!(c, '-' | '_' | '.' | ' '))
}

fn read_json_value(path: &Path) -> Result<Value> {
    let text = std::fs::read_to_string(path)?;
    Ok(serde_json::from_str(&text)?)
}

fn read_json_typed<T: for<'de> Deserialize<'de>>(path: &Path) -> Result<T> {
    let text = std::fs::read_to_string(path)?;
    Ok(serde_json::from_str(&text)?)
}

fn write_json_pretty<T: Serialize>(path: &Path, value: &T) -> Result<()> {
    if let Some(parent) = path.parent() {
        std::fs::create_dir_all(parent)?;
    }
    std::fs::write(path, serde_json::to_vec_pretty(value)?)?;
    Ok(())
}