use std::path::{Path, PathBuf};

use serde::Deserialize;

use crate::TemplateRepoConfig;
use crate::tools::ExternalToolManager;

#[derive(Debug, Deserialize)]
#[allow(dead_code)]
pub struct TemplateInfo {
    pub name: String,
    pub description: String,
    pub match_hint: String,
    /// If true, the agent will wait for user approval after update_plan
    /// before entering the execution phase.
    #[serde(default)]
    pub require_plan_approval: bool,
}

#[allow(dead_code)]
pub struct LoadedTemplate {
    pub id: String,
    pub info: TemplateInfo,
    pub instructions: String,
    pub external_tools: ExternalToolManager,
    pub kb_files: Vec<(String, String)>,
    pub require_plan_approval: bool,
}

#[derive(Debug, Clone, serde::Serialize)]
pub struct TemplateExample {
    pub label: String,
    pub text: String,
}

#[derive(Debug, Clone, serde::Serialize)]
pub struct TemplateListItem {
    pub id: String,
    pub name: String,
    pub description: String,
    pub examples: Vec<TemplateExample>,
}

// --- Template directories ---

fn builtin_dir() -> &'static str {
    if Path::new("/app/templates").is_dir() {
        "/app/templates"
    } else {
        "app-templates"
    }
}

fn default_repo_dir() -> &'static str {
    if Path::new("/app/oseng-templates").is_dir() {
        "/app/oseng-templates"
    } else {
        "oseng-templates"
    }
}

/// For backward compat.
pub fn templates_dir() -> &'static str {
    builtin_dir()
}

// --- Scanning ---

/// Scan a local examples/ directory for .md files.
async fn scan_examples_dir(dir: &Path) -> Vec<TemplateExample> {
    let mut examples = Vec::new();
    let mut entries = match tokio::fs::read_dir(dir).await {
        Ok(e) => e,
        Err(_) => return examples,
    };
    while let Ok(Some(entry)) = entries.next_entry().await {
        let path = entry.path();
        if path.extension().and_then(|e| e.to_str()) != Some("md") {
            continue;
        }
        let label = path
            .file_stem()
            .and_then(|s| s.to_str())
            .unwrap_or("example")
            .to_string();
        if let Ok(text) = tokio::fs::read_to_string(&path).await {
            examples.push(TemplateExample { label, text });
        }
    }
    examples.sort_by(|a, b| a.label.cmp(&b.label));
    examples
}

/// Scan examples from a git repo ref via `git ls-tree` + `git show`.
async fn scan_examples_git(repo: &Path, ref_name: &str, template_path: &str) -> Vec<TemplateExample> {
    let examples_prefix = if template_path.is_empty() {
        "examples/".to_string()
    } else {
        format!("{}/examples/", template_path)
    };

    let tree_output = match tokio::process::Command::new("git")
        .args(["ls-tree", "--name-only", ref_name, &examples_prefix])
        .current_dir(repo)
        .output()
        .await
    {
        Ok(o) if o.status.success() => String::from_utf8_lossy(&o.stdout).to_string(),
        _ => return Vec::new(),
    };

    let mut examples = Vec::new();
    for file_path in tree_output.lines() {
        let file_path = file_path.trim();
        if !file_path.ends_with(".md") {
            continue;
        }
        let label = Path::new(file_path)
            .file_stem()
            .and_then(|s| s.to_str())
            .unwrap_or("example")
            .to_string();

        let show_ref = format!("{}:{}", ref_name, file_path);
        if let Ok(o) = tokio::process::Command::new("git")
            .args(["show", &show_ref])
            .current_dir(repo)
            .output()
            .await
        {
            if o.status.success() {
                let text = String::from_utf8_lossy(&o.stdout).to_string();
                examples.push(TemplateExample { label, text });
            }
        }
    }
    examples.sort_by(|a, b| a.label.cmp(&b.label));
    examples
}

/// Ensure the template repo is a git clone; clone or fetch as needed.
/// Called at startup (before serve) so readiness probe can gate on it.
pub async fn ensure_repo_ready(cfg: &TemplateRepoConfig) {
    let repo = Path::new(&cfg.local_path);
    if repo.join(".git").is_dir() {
        tracing::info!("Template repo already cloned at {}, fetching...", repo.display());
        let _ = tokio::process::Command::new("git")
            .args(["fetch", "--all", "--prune", "-q"])
            .current_dir(repo)
            .env("GIT_SSL_NO_VERIFY", "true")
            .output()
            .await;
        return;
    }

    // Not a git repo — remove stale dir (e.g. COPY'd without .git) and clone
    let url = format!("{}/{}/{}.git", cfg.gitea_url, cfg.owner, cfg.repo);
    tracing::info!("Cloning template repo {} → {}", url, repo.display());
    let _ = tokio::fs::remove_dir_all(repo).await;
    let output = tokio::process::Command::new("git")
        .args(["clone", &url, &repo.to_string_lossy()])
        .env("GIT_SSL_NO_VERIFY", "true")
        .output()
        .await;
    match output {
        Ok(o) if o.status.success() => {
            tracing::info!("Template repo cloned successfully");
        }
        Ok(o) => {
            tracing::error!("git clone failed: {}", String::from_utf8_lossy(&o.stderr));
        }
        Err(e) => {
            tracing::error!("git clone error: {}", e);
        }
    }
}

/// List all templates from both built-in and repo (all branches).
pub async fn list_all_templates(repo_cfg: Option<&TemplateRepoConfig>) -> Vec<TemplateListItem> {
    let mut items = Vec::new();

    // 1. Built-in templates (flat: each top-level dir with template.json)
    let builtin = Path::new(builtin_dir());
    if let Ok(mut entries) = tokio::fs::read_dir(builtin).await {
        while let Ok(Some(entry)) = entries.next_entry().await {
            let is_dir = tokio::fs::metadata(entry.path())
                .await
                .map(|m| m.is_dir())
                .unwrap_or(false);
            if !is_dir {
                continue;
            }
            let id = entry.file_name().to_string_lossy().to_string();
            let meta_path = entry.path().join("template.json");
            if let Ok(data) = tokio::fs::read_to_string(&meta_path).await {
                if let Ok(info) = serde_json::from_str::<TemplateInfo>(&data) {
                    let examples = scan_examples_dir(&entry.path().join("examples")).await;
                    items.push(TemplateListItem {
                        id,
                        name: info.name,
                        description: info.description,
                        examples,
                    });
                }
            }
        }
    }

    // 2. Repo templates (all branches, cloned at startup)
    let repo_path = repo_cfg
        .map(|c| c.local_path.as_str())
        .unwrap_or_else(|| default_repo_dir());
    let repo = Path::new(repo_path);
    if repo.join(".git").is_dir() {
        items.extend(scan_repo_all_branches(repo).await);
    }

    items.sort_by(|a, b| a.id.cmp(&b.id));
    items
}

/// Scan all branches in a git repo for directories containing INSTRUCTIONS.md.
/// Template ID = "{branch}/{path}" e.g. "main/simple-npi", "fam/oncall/network-latency".
async fn scan_repo_all_branches(repo: &Path) -> Vec<TemplateListItem> {
    let mut items = Vec::new();

    // First: git fetch --all to get latest branches
    let _ = tokio::process::Command::new("git")
        .args(["fetch", "--all", "--prune", "-q"])
        .current_dir(repo)
        .output()
        .await;

    // List all remote branches: "origin/main", "origin/fam/foo" etc.
    let output = match tokio::process::Command::new("git")
        .args(["branch", "-r", "--format=%(refname:short)"])
        .current_dir(repo)
        .output()
        .await
    {
        Ok(o) if o.status.success() => String::from_utf8_lossy(&o.stdout).to_string(),
        _ => return items,
    };

    for line in output.lines() {
        let line = line.trim();
        if line.is_empty() || line.contains("HEAD") {
            continue;
        }
        // line = "origin/main" or "origin/fam/feature"
        let branch = match line.strip_prefix("origin/") {
            Some(b) => b,
            None => line,
        };

        // git ls-tree -r --name-only origin/branch
        let tree_output = match tokio::process::Command::new("git")
            .args(["ls-tree", "-r", "--name-only", line])
            .current_dir(repo)
            .output()
            .await
        {
            Ok(o) if o.status.success() => String::from_utf8_lossy(&o.stdout).to_string(),
            _ => continue,
        };

        for file_path in tree_output.lines() {
            let file_path = file_path.trim();
            if !file_path.ends_with("INSTRUCTIONS.md") {
                continue;
            }

            // Template dir path (relative to repo root)
            let template_path = if file_path == "INSTRUCTIONS.md" {
                ""
            } else {
                file_path.trim_end_matches("/INSTRUCTIONS.md")
            };

            let template_id = if template_path.is_empty() {
                branch.to_string()
            } else {
                format!("{}/{}", branch, template_path)
            };

            // Try to read template.json via git show
            let (name, description) = read_git_file_json(repo, line, template_path).await;
            let examples = scan_examples_git(repo, line, template_path).await;

            items.push(TemplateListItem {
                id: template_id.clone(),
                name: name.unwrap_or_else(|| template_id.clone()),
                description: description.unwrap_or_default(),
                examples,
            });
        }
    }

    items
}

/// Read template.json from a git ref via `git show`.
async fn read_git_file_json(
    repo: &Path,
    ref_name: &str,
    template_path: &str,
) -> (Option<String>, Option<String>) {
    let file = if template_path.is_empty() {
        "template.json".to_string()
    } else {
        format!("{}/template.json", template_path)
    };

    let output = match tokio::process::Command::new("git")
        .args(["show", &format!("{}:{}", ref_name, file)])
        .current_dir(repo)
        .output()
        .await
    {
        Ok(o) if o.status.success() => String::from_utf8_lossy(&o.stdout).to_string(),
        _ => return (None, None),
    };

    match serde_json::from_str::<TemplateInfo>(&output) {
        Ok(info) => (Some(info.name), Some(info.description)),
        Err(_) => (None, None),
    }
}

/// Extract a template from a git branch to a local directory.
/// Uses `git archive` to extract the template subtree.
pub async fn extract_repo_template(template_id: &str, repo_cfg: Option<&TemplateRepoConfig>) -> anyhow::Result<PathBuf> {
    let repo_path = repo_cfg
        .map(|c| c.local_path.as_str())
        .unwrap_or_else(|| default_repo_dir());
    let repo = Path::new(repo_path);
    let dest = PathBuf::from("/tmp/tori-repo-templates").join(template_id);
    let _ = tokio::fs::remove_dir_all(&dest).await;
    tokio::fs::create_dir_all(&dest).await?;

    // Parse template_id: "main/simple-npi" → branch="main", path="simple-npi"
    // But branch could be multi-segment: "fam/feature" → need to find split point
    // Strategy: try each split, check if "origin/{prefix}" is a valid ref
    let (ref_name, template_path) = resolve_branch_and_path(repo, template_id).await
        .ok_or_else(|| anyhow::anyhow!("Cannot resolve template: {}", template_id))?;

    // git archive <ref> <path> | tar -x -C <dest> --strip-components=N
    let strip = if template_path.is_empty() {
        0
    } else {
        template_path.matches('/').count() + 1
    };

    let archive_args = if template_path.is_empty() {
        vec!["archive".to_string(), ref_name.clone()]
    } else {
        vec!["archive".to_string(), ref_name.clone(), template_path.clone()]
    };

    let git_archive = tokio::process::Command::new("git")
        .args(&archive_args)
        .current_dir(repo)
        .stdout(std::process::Stdio::piped())
        .spawn()?;

    let child_stdout = git_archive.stdout.unwrap();
    let stdio: std::process::Stdio = child_stdout.try_into()
        .map_err(|e| anyhow::anyhow!("Failed to convert stdout: {:?}", e))?;

    let mut tar_args = vec!["-x".to_string(), "-C".to_string(), dest.to_string_lossy().to_string()];
    if strip > 0 {
        tar_args.push(format!("--strip-components={}", strip));
    }

    let tar_output = tokio::process::Command::new("tar")
        .args(&tar_args)
        .stdin(stdio)
        .output()
        .await?;

    if !tar_output.status.success() {
        anyhow::bail!(
            "tar extract failed: {}",
            String::from_utf8_lossy(&tar_output.stderr)
        );
    }

    // Make scripts in tools/ executable
    let tools_dir = dest.join("tools");
    if tools_dir.is_dir() {
        if let Ok(mut entries) = tokio::fs::read_dir(&tools_dir).await {
            while let Ok(Some(entry)) = entries.next_entry().await {
                let path = entry.path();
                if path.is_file() {
                    #[cfg(unix)]
                    {
                        use std::os::unix::fs::PermissionsExt;
                        if let Ok(meta) = tokio::fs::metadata(&path).await {
                            let mut perms = meta.permissions();
                            perms.set_mode(perms.mode() | 0o111);
                            let _ = tokio::fs::set_permissions(&path, perms).await;
                        }
                    }
                }
            }
        }
    }

    // Make setup executable if present
    let setup_file = dest.join("setup");
    if setup_file.is_file() {
        #[cfg(unix)]
        {
            use std::os::unix::fs::PermissionsExt;
            if let Ok(meta) = tokio::fs::metadata(&setup_file).await {
                let mut perms = meta.permissions();
                perms.set_mode(perms.mode() | 0o111);
                let _ = tokio::fs::set_permissions(&setup_file, perms).await;
            }
        }
    }

    tracing::info!("Extracted repo template '{}' to {}", template_id, dest.display());
    Ok(dest)
}

/// Given a template_id like "main/simple-npi" or "fam/feature/oncall",
/// figure out which part is the branch and which is the path.
async fn resolve_branch_and_path(repo: &Path, template_id: &str) -> Option<(String, String)> {
    let parts: Vec<&str> = template_id.splitn(10, '/').collect();

    // Try progressively longer branch names
    for i in 1..parts.len() + 1 {
        let candidate_branch = parts[..i].join("/");
        let ref_name = format!("origin/{}", candidate_branch);

        let output = tokio::process::Command::new("git")
            .args(["rev-parse", "--verify", &ref_name])
            .current_dir(repo)
            .output()
            .await;

        if let Ok(o) = output {
            if o.status.success() {
                let path = if i < parts.len() {
                    parts[i..].join("/")
                } else {
                    String::new()
                };
                return Some((ref_name, path));
            }
        }
    }

    None
}

/// Check if a template is from the repo (vs built-in).
pub fn is_repo_template(template_id: &str) -> bool {
    // Built-in templates are flat names without '/'
    // Repo templates always have branch/path format
    template_id.contains('/')
}


// --- Template loading ---

/// Run the template's `setup` executable with cwd set to workdir.
/// The template directory is read-only; setup runs in the workdir to initialize
/// the workspace environment (e.g. pulling binaries, installing deps).
pub async fn run_setup(template_dir: &Path, workdir: &str) -> anyhow::Result<()> {
    let setup = template_dir.join("setup");
    if !setup.exists() {
        return Ok(());
    }

    tracing::info!("Running template setup in workdir: {}", workdir);
    let output = tokio::process::Command::new(&setup)
        .current_dir(workdir)
        .output()
        .await
        .map_err(|e| anyhow::anyhow!("Failed to run setup: {}", e))?;

    let stdout = String::from_utf8_lossy(&output.stdout);
    let stderr = String::from_utf8_lossy(&output.stderr);

    if !stdout.is_empty() {
        tracing::info!("setup stdout: {}", stdout.trim_end());
    }
    if !stderr.is_empty() {
        tracing::warn!("setup stderr: {}", stderr.trim_end());
    }

    if !output.status.success() {
        anyhow::bail!(
            "Template setup failed (exit {}): {}",
            output.status.code().unwrap_or(-1),
            stderr.trim_end()
        );
    }

    tracing::info!("Template setup completed successfully");
    Ok(())
}

/// Copy template contents to workdir (excluding template.json, tools/, kb/, INSTRUCTIONS.md).
pub async fn apply_template(template_dir: &Path, workdir: &str) -> anyhow::Result<()> {
    if !template_dir.is_dir() {
        anyhow::bail!("Template directory not found: {}", template_dir.display());
    }
    copy_dir_recursive(template_dir, Path::new(workdir)).await
}

async fn copy_dir_recursive(src: &Path, dst: &Path) -> anyhow::Result<()> {
    let mut stack: Vec<(PathBuf, PathBuf, bool)> =
        vec![(src.to_path_buf(), dst.to_path_buf(), true)];

    while let Some((src_dir, dst_dir, top_level)) = stack.pop() {
        tokio::fs::create_dir_all(&dst_dir).await?;
        let mut entries = tokio::fs::read_dir(&src_dir).await?;
        while let Some(entry) = entries.next_entry().await? {
            let name = entry.file_name();
            let name_str = name.to_string_lossy();

            if top_level
                && (name_str == "template.json"
                    || name_str == "tools"
                    || name_str == "kb"
                    || name_str == "examples"
                    || name_str == "setup"
                    || name_str == "INSTRUCTIONS.md")
            {
                continue;
            }

            let src_path = entry.path();
            let dst_path = dst_dir.join(&name);

            if entry.file_type().await?.is_dir() {
                stack.push((src_path, dst_path, false));
            } else {
                tokio::fs::copy(&src_path, &dst_path).await?;
            }
        }
    }
    Ok(())
}

impl LoadedTemplate {
    pub async fn load_from_dir(template_id: &str, base: &Path) -> anyhow::Result<Self> {
        if !base.is_dir() {
            anyhow::bail!("Template directory not found: {}", base.display());
        }

        let meta_path = base.join("template.json");
        let info = if let Ok(data) = tokio::fs::read_to_string(&meta_path).await {
            serde_json::from_str::<TemplateInfo>(&data).unwrap_or_else(|_| TemplateInfo {
                name: template_id.to_string(),
                description: String::new(),
                match_hint: String::new(),
                require_plan_approval: false,
            })
        } else {
            TemplateInfo {
                name: template_id.to_string(),
                description: String::new(),
                match_hint: String::new(),
                require_plan_approval: false,
            }
        };

        let instructions = tokio::fs::read_to_string(base.join("INSTRUCTIONS.md"))
            .await
            .unwrap_or_default();

        let external_tools = ExternalToolManager::discover(base).await;
        tracing::info!("Template '{}': {} external tools", template_id, external_tools.len());

        let kb_dir = base.join("kb");
        let kb_files = scan_kb_files(&kb_dir).await;
        tracing::info!("Template '{}': {} KB files", template_id, kb_files.len());

        let require_plan_approval = info.require_plan_approval;

        Ok(Self {
            id: template_id.to_string(),
            info,
            instructions,
            external_tools,
            kb_files,
            require_plan_approval,
        })
    }

    pub async fn load(template_id: &str) -> anyhow::Result<Self> {
        let base = Path::new(builtin_dir()).join(template_id);
        Self::load_from_dir(template_id, &base).await
    }
}

async fn scan_kb_files(kb_dir: &Path) -> Vec<(String, String)> {
    let mut results = Vec::new();

    let mut entries = match tokio::fs::read_dir(kb_dir).await {
        Ok(e) => e,
        Err(_) => return results,
    };

    while let Ok(Some(entry)) = entries.next_entry().await {
        let path = entry.path();
        let real_path = match tokio::fs::canonicalize(&path).await {
            Ok(p) => p,
            Err(_) => path.clone(),
        };

        let ext = real_path.extension().and_then(|e| e.to_str()).unwrap_or("");
        if ext != "md" {
            continue;
        }

        let content = match tokio::fs::read_to_string(&real_path).await {
            Ok(c) => c,
            Err(e) => {
                tracing::warn!("Failed to read KB file {}: {}", real_path.display(), e);
                continue;
            }
        };

        let title = content
            .lines()
            .find(|l| l.starts_with("# "))
            .map(|l| l.trim_start_matches("# ").trim().to_string())
            .unwrap_or_else(|| {
                path.file_stem()
                    .and_then(|s| s.to_str())
                    .unwrap_or("untitled")
                    .to_string()
            });

        results.push((title, content));
    }

    results
}