//! Defines the protocol for a Codex session between a client and an agent.
//!
//! Uses a SQ (Submission Queue) / EQ (Event Queue) pattern to asynchronously communicate
//! between user and agent.

use std::collections::HashMap;
use std::path::PathBuf;

use serde::Deserialize;
use serde::Serialize;

/// Submission Queue Entry - requests from user
#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct Submission {
    /// Unique id for this Submission to correlate with Events
    pub id: String,
    /// Payload
    pub op: Op,
}

/// Submission operation
#[derive(Debug, Clone, Deserialize, Serialize)]
#[serde(tag = "type", rename_all = "snake_case")]
#[non_exhaustive]
pub enum Op {
    /// Configure the model session.
    ConfigureSession {
        /// If not specified, server will use its default model.
        model: Option<String>,
        /// Model instructions
        instructions: Option<String>,
        /// When to escalate for approval for execution
        approval_policy: AskForApproval,
        /// How to sandbox commands executed in the system
        sandbox_policy: SandboxPolicy,
    },

    /// Abort current task.
    /// This server sends no corresponding Event
    Interrupt,

    /// Input from the user
    UserInput {
        /// User input items, see `InputItem`
        items: Vec<InputItem>,
    },

    /// Approve a command execution
    ExecApproval {
        /// The id of the submission we are approving
        id: String,
        /// The user's decision in response to the request.
        decision: ReviewDecision,
    },

    /// Approve a code patch
    PatchApproval {
        /// The id of the submission we are approving
        id: String,
        /// The user's decision in response to the request.
        decision: ReviewDecision,
    },
}

/// Determines how liberally commands are auto‑approved by the system.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum AskForApproval {
    /// Under this policy, only “known safe” commands—as determined by
    /// `is_safe_command()`—that **only read files** are auto‑approved.
    /// Everything else will ask the user to approve.
    UnlessAllowListed,

    /// In addition to everything allowed by **`Suggest`**, commands that
    /// *write* to files **within the user’s approved list of writable paths**
    /// are also auto‑approved.
    /// TODO(ragona): fix
    AutoEdit,

    /// *All* commands are auto‑approved, but they are expected to run inside a
    /// sandbox where network access is disabled and writes are confined to a
    /// specific set of paths. If the command fails, it will be escalated to
    /// the user to approve execution without a sandbox.
    OnFailure,

    /// Never ask the user to approve commands. Failures are immediately returned
    /// to the model, and never escalated to the user for approval.
    Never,
}

/// Determines execution restrictions for model shell commands
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum SandboxPolicy {
    /// Network syscalls will be blocked
    NetworkRestricted,
    /// Filesystem writes will be restricted
    FileWriteRestricted,
    /// Network and filesystem writes will be restricted
    NetworkAndFileWriteRestricted,
    /// No restrictions; full "unsandboxed" mode
    DangerousNoRestrictions,
}

/// User input
#[non_exhaustive]
#[derive(Debug, Clone, Deserialize, Serialize)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum InputItem {
    Text {
        text: String,
    },
    /// Pre‑encoded data: URI image.
    Image {
        image_url: String,
    },

    /// Local image path provided by the user.  This will be converted to an
    /// `Image` variant (base64 data URL) during request serialization.
    LocalImage {
        path: std::path::PathBuf,
    },
}

/// Event Queue Entry - events from agent
#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct Event {
    /// Submission `id` that this event is correlated with.
    pub id: String,
    /// Payload
    pub msg: EventMsg,
}

/// Response event from the agent
#[non_exhaustive]
#[derive(Debug, Clone, Deserialize, Serialize)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum EventMsg {
    /// Error while executing a submission
    Error {
        message: String,
    },

    /// Agent has started a task
    TaskStarted,

    /// Agent has completed all actions
    TaskComplete,

    /// Agent text output message
    AgentMessage {
        message: String,
    },

    /// Ack the client's configure message.
    SessionConfigured {
        /// Tell the client what model is being queried.
        model: String,
    },

    /// Notification that the server is about to execute a command.
    ExecCommandBegin {
        /// Identifier so this can be paired with the ExecCommandEnd event.
        call_id: String,
        /// The command to be executed.
        command: Vec<String>,
        /// The command's working directory if not the default cwd for the
        /// agent.
        cwd: String,
    },

    ExecCommandEnd {
        /// Identifier for the ExecCommandBegin that finished.
        call_id: String,
        /// Captured stdout
        stdout: String,
        /// Captured stderr
        stderr: String,
        /// The command's exit code.
        exit_code: i32,
    },

    ExecApprovalRequest {
        /// The command to be executed.
        command: Vec<String>,
        /// The command's working directory.
        cwd: PathBuf,
        /// Optional human‑readable reason for the approval (e.g. retry without
        /// sandbox).
        #[serde(skip_serializing_if = "Option::is_none")]
        reason: Option<String>,
    },

    ApplyPatchApprovalRequest {
        changes: HashMap<PathBuf, FileChange>,
        /// Optional explanatory reason (e.g. request for extra write access).
        #[serde(skip_serializing_if = "Option::is_none")]
        reason: Option<String>,

        /// When set, the agent is asking the user to allow writes under this
        /// root for the remainder of the session.
        #[serde(skip_serializing_if = "Option::is_none")]
        grant_root: Option<PathBuf>,
    },

    BackgroundEvent {
        message: String,
    },

    /// Notification that the agent is about to apply a code patch. Mirrors
    /// `ExecCommandBegin` so front‑ends can show progress indicators.
    PatchApplyBegin {
        /// Identifier so this can be paired with the PatchApplyEnd event.
        call_id: String,

        /// If true, there was no ApplyPatchApprovalRequest for this patch.
        auto_approved: bool,

        /// The changes to be applied.
        changes: HashMap<PathBuf, FileChange>,
    },

    /// Notification that a patch application has finished.
    PatchApplyEnd {
        /// Identifier for the PatchApplyBegin that finished.
        call_id: String,
        /// Captured stdout (summary printed by apply_patch).
        stdout: String,
        /// Captured stderr (parser errors, IO failures, etc.).
        stderr: String,
        /// Whether the patch was applied successfully.
        success: bool,
    },
}

/// User's decision in response to an ExecApprovalRequest.
#[derive(Debug, Default, Clone, Copy, Deserialize, Serialize)]
#[serde(rename_all = "snake_case")]
pub enum ReviewDecision {
    /// User has approved this command and the agent should execute it.
    Approved,

    /// User has approved this command and wants to automatically approve any
    /// future identical instances (`command` and `cwd` match exactly) for the
    /// remainder of the session.
    ApprovedForSession,

    /// User has denied this command and the agent should not execute it, but
    /// it should continue the session and try something else.
    #[default]
    Denied,

    /// User has denied this command and the agent should not do anything until
    /// the user's next command.
    Abort,
}

#[derive(Debug, Clone, Deserialize, Serialize)]
#[serde(rename_all = "snake_case")]
pub enum FileChange {
    Add {
        content: String,
    },
    Delete,
    Update {
        unified_diff: String,
        move_path: Option<PathBuf>,
    },
}

#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct Chunk {
    /// 1-based line index of the first line in the original file
    pub orig_index: u32,
    pub deleted_lines: Vec<String>,
    pub inserted_lines: Vec<String>,
}