use super::traits::{Tool, ToolResult};
use crate::security::SecurityPolicy;
use async_trait::async_trait;
use serde_json::json;
use std::sync::Arc;

const MAX_WRITE_DIFF_CHARS: usize = 12_000;

/// Write file contents with path sandboxing
pub struct FileWriteTool {
    security: Arc<SecurityPolicy>,
}

impl FileWriteTool {
    pub fn new(security: Arc<SecurityPolicy>) -> Self {
        Self { security }
    }
}

fn push_prefixed_lines(out: &mut String, prefix: char, value: &str) {
    if value.is_empty() {
        out.push(prefix);
        out.push('\n');
        return;
    }
    for line in value.lines() {
        out.push(prefix);
        out.push_str(line);
        out.push('\n');
    }
}

fn truncate_diff(diff: String) -> String {
    if diff.len() <= MAX_WRITE_DIFF_CHARS {
        return diff;
    }
    let mut truncated = diff.chars().take(MAX_WRITE_DIFF_CHARS).collect::<String>();
    truncated.push_str("\n[Diff truncated]");
    truncated
}

fn render_write_diff(path: &str, previous: Option<&str>, next: &str) -> Option<String> {
    if previous == Some(next) {
        return None;
    }
    let mut diff = String::new();
    diff.push_str("--- ");
    diff.push_str(previous.map(|_| path).unwrap_or("/dev/null"));
    diff.push('\n');
    diff.push_str("+++ ");
    diff.push_str(path);
    diff.push('\n');
    diff.push_str("@@\n");
    if let Some(previous) = previous {
        push_prefixed_lines(&mut diff, '-', previous);
    }
    push_prefixed_lines(&mut diff, '+', next);
    Some(truncate_diff(diff))
}

#[async_trait]
impl Tool for FileWriteTool {
    fn name(&self) -> &str {
        "file_write"
    }

    fn description(&self) -> &str {
        "Write contents to a file in the workspace"
    }

    fn parameters_schema(&self) -> serde_json::Value {
        json!({
            "type": "object",
            "properties": {
                "path": {
                    "type": "string",
                    "description": "Path to the file. Relative paths resolve from workspace; outside paths require policy allowlist."
                },
                "content": {
                    "type": "string",
                    "description": "Content to write to the file"
                }
            },
            "required": ["path", "content"]
        })
    }

    async fn execute(&self, args: serde_json::Value) -> anyhow::Result<ToolResult> {
        let path = args
            .get("path")
            .and_then(|v| v.as_str())
            .ok_or_else(|| anyhow::anyhow!("Missing 'path' parameter"))?;

        let content = args
            .get("content")
            .and_then(|v| v.as_str())
            .ok_or_else(|| anyhow::anyhow!("Missing 'content' parameter"))?;

        if !self.security.can_act() {
            return Ok(ToolResult {
                success: false,
                output: String::new(),
                error: Some("Action blocked: autonomy is read-only".into()),
            });
        }

        if self.security.is_rate_limited() {
            return Ok(ToolResult {
                success: false,
                output: String::new(),
                error: Some("Rate limit exceeded: too many actions in the last hour".into()),
            });
        }

        // Security check: validate path is within workspace
        if !self.security.is_path_allowed(path) {
            return Ok(ToolResult {
                success: false,
                output: String::new(),
                error: Some(format!("Path not allowed by security policy: {path}")),
            });
        }

        let full_path = self.security.resolve_tool_path(path);

        let Some(parent) = full_path.parent() else {
            return Ok(ToolResult {
                success: false,
                output: String::new(),
                error: Some("Invalid path: missing parent directory".into()),
            });
        };

        // Ensure parent directory exists
        tokio::fs::create_dir_all(parent).await?;

        // Resolve parent AFTER creation to block symlink escapes.
        let resolved_parent = match tokio::fs::canonicalize(parent).await {
            Ok(p) => p,
            Err(e) => {
                return Ok(ToolResult {
                    success: false,
                    output: String::new(),
                    error: Some(format!("Failed to resolve file path: {e}")),
                });
            }
        };

        if !self.security.is_resolved_path_allowed(&resolved_parent) {
            return Ok(ToolResult {
                success: false,
                output: String::new(),
                error: Some(
                    self.security
                        .resolved_path_violation_message(&resolved_parent),
                ),
            });
        }

        let Some(file_name) = full_path.file_name() else {
            return Ok(ToolResult {
                success: false,
                output: String::new(),
                error: Some("Invalid path: missing file name".into()),
            });
        };

        let resolved_target = resolved_parent.join(file_name);

        if self.security.is_runtime_config_path(&resolved_target) {
            return Ok(ToolResult {
                success: false,
                output: String::new(),
                error: Some(
                    self.security
                        .runtime_config_violation_message(&resolved_target),
                ),
            });
        }

        // If the target already exists and is a symlink, refuse to follow it
        if let Ok(meta) = tokio::fs::symlink_metadata(&resolved_target).await {
            if meta.file_type().is_symlink() {
                return Ok(ToolResult {
                    success: false,
                    output: String::new(),
                    error: Some(format!(
                        "Refusing to write through symlink: {}",
                        resolved_target.display()
                    )),
                });
            }
        }

        if !self.security.record_action() {
            return Ok(ToolResult {
                success: false,
                output: String::new(),
                error: Some("Rate limit exceeded: action budget exhausted".into()),
            });
        }

        let previous_content = tokio::fs::read_to_string(&resolved_target).await.ok();

        match tokio::fs::write(&resolved_target, content).await {
            Ok(()) => {
                let mut output = format!("Written {} bytes to {path}", content.len());
                if let Some(diff) = render_write_diff(path, previous_content.as_deref(), content) {
                    output.push_str("\n\nDiff\n");
                    output.push_str(&diff);
                }
                Ok(ToolResult {
                    success: true,
                    output,
                    error: None,
                })
            }
            Err(e) => Ok(ToolResult {
                success: false,
                output: String::new(),
                error: Some(format!("Failed to write file: {e}")),
            }),
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::security::{AutonomyLevel, SecurityPolicy};

    fn test_security(workspace: std::path::PathBuf) -> Arc<SecurityPolicy> {
        Arc::new(SecurityPolicy {
            autonomy: AutonomyLevel::Supervised,
            workspace_dir: workspace,
            ..SecurityPolicy::default()
        })
    }

    fn test_security_with(
        workspace: std::path::PathBuf,
        autonomy: AutonomyLevel,
        max_actions_per_hour: u32,
    ) -> Arc<SecurityPolicy> {
        Arc::new(SecurityPolicy {
            autonomy,
            workspace_dir: workspace,
            max_actions_per_hour,
            ..SecurityPolicy::default()
        })
    }

    #[test]
    fn file_write_name() {
        let tool = FileWriteTool::new(test_security(std::env::temp_dir()));
        assert_eq!(tool.name(), "file_write");
    }

    #[test]
    fn file_write_schema_has_path_and_content() {
        let tool = FileWriteTool::new(test_security(std::env::temp_dir()));
        let schema = tool.parameters_schema();
        assert!(schema["properties"]["path"].is_object());
        assert!(schema["properties"]["content"].is_object());
        let required = schema["required"].as_array().unwrap();
        assert!(required.contains(&json!("path")));
        assert!(required.contains(&json!("content")));
    }

    #[tokio::test]
    async fn file_write_creates_file() {
        let dir = std::env::temp_dir().join("revka_test_file_write");
        let _ = tokio::fs::remove_dir_all(&dir).await;
        tokio::fs::create_dir_all(&dir).await.unwrap();

        let tool = FileWriteTool::new(test_security(dir.clone()));
        let result = tool
            .execute(json!({"path": "out.txt", "content": "written!"}))
            .await
            .unwrap();
        assert!(result.success);
        assert!(result.output.contains("8 bytes"));

        let content = tokio::fs::read_to_string(dir.join("out.txt"))
            .await
            .unwrap();
        assert_eq!(content, "written!");

        let _ = tokio::fs::remove_dir_all(&dir).await;
    }

    #[tokio::test]
    async fn file_write_creates_parent_dirs() {
        let dir = std::env::temp_dir().join("revka_test_file_write_nested");
        let _ = tokio::fs::remove_dir_all(&dir).await;
        tokio::fs::create_dir_all(&dir).await.unwrap();

        let tool = FileWriteTool::new(test_security(dir.clone()));
        let result = tool
            .execute(json!({"path": "a/b/c/deep.txt", "content": "deep"}))
            .await
            .unwrap();
        assert!(result.success);

        let content = tokio::fs::read_to_string(dir.join("a/b/c/deep.txt"))
            .await
            .unwrap();
        assert_eq!(content, "deep");

        let _ = tokio::fs::remove_dir_all(&dir).await;
    }

    #[tokio::test]
    async fn file_write_normalizes_workspace_prefixed_relative_path() {
        let root = std::env::temp_dir().join("revka_test_file_write_workspace_prefixed");
        let workspace = root.join("workspace");
        let _ = tokio::fs::remove_dir_all(&root).await;
        tokio::fs::create_dir_all(&workspace).await.unwrap();

        let tool = FileWriteTool::new(test_security(workspace.clone()));
        let workspace_prefixed = workspace
            .strip_prefix(std::path::Path::new("/"))
            .unwrap()
            .join("nested/out.txt");
        let result = tool
            .execute(json!({
                "path": workspace_prefixed.to_string_lossy(),
                "content": "written!"
            }))
            .await
            .unwrap();
        assert!(result.success);

        let content = tokio::fs::read_to_string(workspace.join("nested/out.txt"))
            .await
            .unwrap();
        assert_eq!(content, "written!");
        assert!(!workspace.join(workspace_prefixed).exists());

        let _ = tokio::fs::remove_dir_all(&root).await;
    }

    #[tokio::test]
    async fn file_write_overwrites_existing() {
        let dir = std::env::temp_dir().join("revka_test_file_write_overwrite");
        let _ = tokio::fs::remove_dir_all(&dir).await;
        tokio::fs::create_dir_all(&dir).await.unwrap();
        tokio::fs::write(dir.join("exist.txt"), "old")
            .await
            .unwrap();

        let tool = FileWriteTool::new(test_security(dir.clone()));
        let result = tool
            .execute(json!({"path": "exist.txt", "content": "new"}))
            .await
            .unwrap();
        assert!(result.success);
        assert!(result.output.contains("--- exist.txt"));
        assert!(result.output.contains("+++ exist.txt"));
        assert!(result.output.contains("-old"));
        assert!(result.output.contains("+new"));

        let content = tokio::fs::read_to_string(dir.join("exist.txt"))
            .await
            .unwrap();
        assert_eq!(content, "new");

        let _ = tokio::fs::remove_dir_all(&dir).await;
    }

    #[tokio::test]
    async fn file_write_blocks_path_traversal() {
        let dir = std::env::temp_dir().join("revka_test_file_write_traversal");
        let _ = tokio::fs::remove_dir_all(&dir).await;
        tokio::fs::create_dir_all(&dir).await.unwrap();

        let tool = FileWriteTool::new(test_security(dir.clone()));
        let result = tool
            .execute(json!({"path": "../../etc/evil", "content": "bad"}))
            .await
            .unwrap();
        assert!(!result.success);
        assert!(result.error.as_ref().unwrap().contains("not allowed"));

        let _ = tokio::fs::remove_dir_all(&dir).await;
    }

    #[tokio::test]
    async fn file_write_blocks_absolute_path() {
        let tool = FileWriteTool::new(test_security(std::env::temp_dir()));
        let result = tool
            .execute(json!({"path": "/etc/evil", "content": "bad"}))
            .await
            .unwrap();
        assert!(!result.success);
        assert!(result.error.as_ref().unwrap().contains("not allowed"));
    }

    #[tokio::test]
    async fn file_write_missing_path_param() {
        let tool = FileWriteTool::new(test_security(std::env::temp_dir()));
        let result = tool.execute(json!({"content": "data"})).await;
        assert!(result.is_err());
    }

    #[tokio::test]
    async fn file_write_missing_content_param() {
        let tool = FileWriteTool::new(test_security(std::env::temp_dir()));
        let result = tool.execute(json!({"path": "file.txt"})).await;
        assert!(result.is_err());
    }

    #[tokio::test]
    async fn file_write_empty_content() {
        let dir = std::env::temp_dir().join("revka_test_file_write_empty");
        let _ = tokio::fs::remove_dir_all(&dir).await;
        tokio::fs::create_dir_all(&dir).await.unwrap();

        let tool = FileWriteTool::new(test_security(dir.clone()));
        let result = tool
            .execute(json!({"path": "empty.txt", "content": ""}))
            .await
            .unwrap();
        assert!(result.success);
        assert!(result.output.contains("0 bytes"));

        let _ = tokio::fs::remove_dir_all(&dir).await;
    }

    #[cfg(unix)]
    #[tokio::test]
    async fn file_write_blocks_symlink_escape() {
        use std::os::unix::fs::symlink;

        let root = std::env::temp_dir().join("revka_test_file_write_symlink_escape");
        let workspace = root.join("workspace");
        let outside = root.join("outside");

        let _ = tokio::fs::remove_dir_all(&root).await;
        tokio::fs::create_dir_all(&workspace).await.unwrap();
        tokio::fs::create_dir_all(&outside).await.unwrap();

        symlink(&outside, workspace.join("escape_dir")).unwrap();

        let tool = FileWriteTool::new(test_security(workspace.clone()));
        let result = tool
            .execute(json!({"path": "escape_dir/hijack.txt", "content": "bad"}))
            .await
            .unwrap();

        assert!(!result.success);
        assert!(
            result
                .error
                .as_deref()
                .unwrap_or("")
                .contains("escapes workspace")
        );
        assert!(!outside.join("hijack.txt").exists());

        let _ = tokio::fs::remove_dir_all(&root).await;
    }

    #[tokio::test]
    async fn file_write_blocks_readonly_mode() {
        let dir = std::env::temp_dir().join("revka_test_file_write_readonly");
        let _ = tokio::fs::remove_dir_all(&dir).await;
        tokio::fs::create_dir_all(&dir).await.unwrap();

        let tool = FileWriteTool::new(test_security_with(dir.clone(), AutonomyLevel::ReadOnly, 20));
        let result = tool
            .execute(json!({"path": "out.txt", "content": "should-block"}))
            .await
            .unwrap();

        assert!(!result.success);
        assert!(result.error.as_deref().unwrap_or("").contains("read-only"));
        assert!(!dir.join("out.txt").exists());

        let _ = tokio::fs::remove_dir_all(&dir).await;
    }

    #[tokio::test]
    async fn file_write_blocks_when_rate_limited() {
        let dir = std::env::temp_dir().join("revka_test_file_write_rate_limited");
        let _ = tokio::fs::remove_dir_all(&dir).await;
        tokio::fs::create_dir_all(&dir).await.unwrap();

        let tool = FileWriteTool::new(test_security_with(
            dir.clone(),
            AutonomyLevel::Supervised,
            0,
        ));
        let result = tool
            .execute(json!({"path": "out.txt", "content": "should-block"}))
            .await
            .unwrap();

        assert!(!result.success);
        assert!(
            result
                .error
                .as_deref()
                .unwrap_or("")
                .contains("Rate limit exceeded")
        );
        assert!(!dir.join("out.txt").exists());

        let _ = tokio::fs::remove_dir_all(&dir).await;
    }

    // ── §5.1 TOCTOU / symlink file write protection tests ────

    #[cfg(unix)]
    #[tokio::test]
    async fn file_write_blocks_symlink_target_file() {
        use std::os::unix::fs::symlink;

        let root = std::env::temp_dir().join("revka_test_file_write_symlink_target");
        let workspace = root.join("workspace");
        let outside = root.join("outside");

        let _ = tokio::fs::remove_dir_all(&root).await;
        tokio::fs::create_dir_all(&workspace).await.unwrap();
        tokio::fs::create_dir_all(&outside).await.unwrap();

        // Create a file outside and symlink to it inside workspace
        tokio::fs::write(outside.join("target.txt"), "original")
            .await
            .unwrap();
        symlink(outside.join("target.txt"), workspace.join("linked.txt")).unwrap();

        let tool = FileWriteTool::new(test_security(workspace.clone()));
        let result = tool
            .execute(json!({"path": "linked.txt", "content": "overwritten"}))
            .await
            .unwrap();

        assert!(!result.success, "writing through symlink must be blocked");
        assert!(
            result.error.as_deref().unwrap_or("").contains("symlink"),
            "error should mention symlink"
        );

        // Verify original file was not modified
        let content = tokio::fs::read_to_string(outside.join("target.txt"))
            .await
            .unwrap();
        assert_eq!(content, "original", "original file must not be modified");

        let _ = tokio::fs::remove_dir_all(&root).await;
    }

    #[tokio::test]
    async fn file_write_absolute_path_in_workspace() {
        let dir = std::env::temp_dir().join("revka_test_file_write_abs_path");
        let _ = tokio::fs::remove_dir_all(&dir).await;
        tokio::fs::create_dir_all(&dir).await.unwrap();

        // Canonicalize so the workspace dir matches resolved paths on macOS (/private/var/…)
        let dir = tokio::fs::canonicalize(&dir).await.unwrap();

        let tool = FileWriteTool::new(test_security(dir.clone()));

        // Pass an absolute path that is within the workspace
        let abs_path = dir.join("abs_test.txt");
        let result = tool
            .execute(
                json!({"path": abs_path.to_string_lossy().to_string(), "content": "absolute!"}),
            )
            .await
            .unwrap();

        assert!(
            result.success,
            "writing via absolute workspace path should succeed, error: {:?}",
            result.error
        );

        let content = tokio::fs::read_to_string(dir.join("abs_test.txt"))
            .await
            .unwrap();
        assert_eq!(content, "absolute!");

        let _ = tokio::fs::remove_dir_all(&dir).await;
    }

    #[tokio::test]
    async fn file_write_blocks_null_byte_in_path() {
        let dir = std::env::temp_dir().join("revka_test_file_write_null");
        let _ = tokio::fs::remove_dir_all(&dir).await;
        tokio::fs::create_dir_all(&dir).await.unwrap();

        let tool = FileWriteTool::new(test_security(dir.clone()));
        let result = tool
            .execute(json!({"path": "file\u{0000}.txt", "content": "bad"}))
            .await
            .unwrap();
        assert!(!result.success, "paths with null bytes must be blocked");

        let _ = tokio::fs::remove_dir_all(&dir).await;
    }

    #[tokio::test]
    async fn file_write_blocks_runtime_config_path() {
        let root = std::env::temp_dir().join("revka_test_file_write_runtime_config");
        let workspace = root.join("workspace");
        let config_path = root.join("config.toml");
        let _ = tokio::fs::remove_dir_all(&root).await;
        tokio::fs::create_dir_all(&workspace).await.unwrap();

        let security = Arc::new(SecurityPolicy {
            autonomy: AutonomyLevel::Supervised,
            workspace_dir: workspace.clone(),
            workspace_only: false,
            allowed_roots: vec![root.clone()],
            forbidden_paths: vec![],
            ..SecurityPolicy::default()
        });
        let tool = FileWriteTool::new(security);
        let result = tool
            .execute(json!({
                "path": config_path.to_string_lossy(),
                "content": "auto_approve = [\"cron_add\"]"
            }))
            .await
            .unwrap();

        assert!(!result.success);
        assert!(
            result
                .error
                .unwrap_or_default()
                .contains("runtime config/state file")
        );

        let _ = tokio::fs::remove_dir_all(&root).await;
    }
}
