//! Pipeline Executor
//!
//! Executes pipelines step by step, managing state and calling actions.

use std::sync::Arc;
use std::collections::HashMap;
use tokio::sync::RwLock;
use serde_json::Value;
use uuid::Uuid;
use chrono::Utc;
use futures::stream::{self, StreamExt};
use futures::future::{BoxFuture, FutureExt};

use crate::types::{Pipeline, PipelineRun, PipelineProgress, RunStatus, PipelineStep, Action, ExportFormat};
use crate::state::{ExecutionContext, StateError};
use crate::actions::ActionRegistry;

/// Pipeline execution errors
#[derive(Debug, thiserror::Error)]
pub enum ExecuteError {
    #[error("State error: {0}")]
    State(#[from] StateError),

    #[error("Action error: {0}")]
    Action(String),

    #[error("Step not found: {0}")]
    StepNotFound(String),

    #[error("Timeout exceeded")]
    Timeout,

    #[error("Cancelled")]
    Cancelled,

    #[error("Condition not met: {0}")]
    ConditionNotMet(String),

    #[error("IO error: {0}")]
    Io(#[from] std::io::Error),
}

/// Pipeline executor
pub struct PipelineExecutor {
    /// Action registry
    action_registry: Arc<ActionRegistry>,

    /// Active runs (run_id -> run state)
    runs: RwLock<HashMap<String, PipelineRun>>,

    /// Cancellation flags
    cancellations: RwLock<HashMap<String, bool>>,
}

impl PipelineExecutor {
    /// Create a new executor
    pub fn new(action_registry: Arc<ActionRegistry>) -> Self {
        Self {
            action_registry,
            runs: RwLock::new(HashMap::new()),
            cancellations: RwLock::new(HashMap::new()),
        }
    }

    /// Execute a pipeline with auto-generated run ID
    pub async fn execute(
        &self,
        pipeline: &Pipeline,
        inputs: HashMap<String, Value>,
    ) -> Result<PipelineRun, ExecuteError> {
        let run_id = Uuid::new_v4().to_string();
        self.execute_with_id(pipeline, inputs, &run_id).await
    }

    /// Execute a pipeline with a specific run ID
    ///
    /// Use this when you need to know the run_id before execution starts,
    /// e.g., for async spawning where the caller needs to track progress.
    pub async fn execute_with_id(
        &self,
        pipeline: &Pipeline,
        inputs: HashMap<String, Value>,
        run_id: &str,
    ) -> Result<PipelineRun, ExecuteError> {
        let pipeline_id = pipeline.metadata.name.clone();
        let run_id = run_id.to_string();

        // Create run record
        let run = PipelineRun {
            id: run_id.clone(),
            pipeline_id: pipeline_id.clone(),
            status: RunStatus::Running,
            inputs: serde_json::to_value(&inputs).unwrap_or(Value::Null),
            current_step: None,
            step_results: HashMap::new(),
            outputs: None,
            error: None,
            started_at: Utc::now(),
            ended_at: None,
        };

        // Store run
        self.runs.write().await.insert(run_id.clone(), run);

        // Create execution context
        let mut context = ExecutionContext::new(inputs);

        // Execute steps
        let result = self.execute_steps(pipeline, &mut context, &run_id).await;

        // Update run state
        let mut runs = self.runs.write().await;
        if let Some(run) = runs.get_mut(&run_id) {
            match result {
                Ok(outputs) => {
                    run.status = RunStatus::Completed;
                    run.outputs = Some(serde_json::to_value(&outputs).unwrap_or(Value::Null));
                }
                Err(e) => {
                    run.status = RunStatus::Failed;
                    run.error = Some(e.to_string());
                }
            }
            run.ended_at = Some(Utc::now());
            return Ok(run.clone());
        }

        Err(ExecuteError::Action("执行后未找到运行记录".to_string()))
    }

    /// Execute pipeline steps
    async fn execute_steps(
        &self,
        pipeline: &Pipeline,
        context: &mut ExecutionContext,
        run_id: &str,
    ) -> Result<HashMap<String, Value>, ExecuteError> {
        let total_steps = pipeline.spec.steps.len();

        for (idx, step) in pipeline.spec.steps.iter().enumerate() {
            // Check cancellation
            if *self.cancellations.read().await.get(run_id).unwrap_or(&false) {
                return Err(ExecuteError::Cancelled);
            }

            // Update current step
            if let Some(run) = self.runs.write().await.get_mut(run_id) {
                run.current_step = Some(step.id.clone());
            }

            // Check condition
            if let Some(condition) = &step.when {
                let should_execute = self.evaluate_condition(condition, context)?;
                if !should_execute {
                    tracing::info!("Skipping step {} (condition not met)", step.id);
                    continue;
                }
            }

            tracing::info!("Executing step {} ({}/{})", step.id, idx + 1, total_steps);

            // Execute action
            let result = self.execute_action(&step.action, context).await?;

            // Store result
            context.set_output(&step.id, result.clone());

            // Update step results in run
            if let Some(run) = self.runs.write().await.get_mut(run_id) {
                run.step_results.insert(step.id.clone(), result);
            }
        }

        // Extract outputs
        Ok(context.extract_outputs(&pipeline.spec.outputs)
            .map_err(ExecuteError::State)?)
    }

    /// Execute a single action (returns BoxFuture for recursion support)
    fn execute_action<'a>(
        &'a self,
        action: &'a Action,
        context: &'a mut ExecutionContext,
    ) -> BoxFuture<'a, Result<Value, ExecuteError>> {
        async move {
            match action {
                Action::LlmGenerate { template, input, model, temperature, max_tokens, json_mode } => {
                    tracing::debug!(target: "pipeline_executor", "LlmGenerate action called");
                    tracing::debug!(target: "pipeline_executor", "input keys: {:?}", input.keys().collect::<Vec<_>>());

                    // First resolve the template itself (handles ${inputs.xxx}, ${item.xxx}, etc.)
                    let resolved_template = context.resolve(template)?;
                    let resolved_template_str = resolved_template.as_str().unwrap_or(template).to_string();
                    tracing::debug!(target: "pipeline_executor", "Resolved template ({} chars, first 100): {}",
                        resolved_template_str.len(),
                        &resolved_template_str[..resolved_template_str.len().min(100)]);

                    let resolved_input = context.resolve_map(input)?;
                    tracing::debug!(target: "pipeline_executor", "Resolved input keys: {:?}", resolved_input.keys().collect::<Vec<_>>());
                    self.action_registry.execute_llm(
                        &resolved_template_str,
                        resolved_input,
                        model.clone(),
                        *temperature,
                        *max_tokens,
                        *json_mode,
                    ).await.map_err(|e| ExecuteError::Action(e.to_string()))
                }

                Action::Parallel { each, step, max_workers } => {
                    let items = context.resolve(each)?;
                    let items_array = items.as_array()
                        .ok_or_else(|| ExecuteError::Action("并行执行 'each' 必须解析为数组".to_string()))?;

                    let workers = max_workers.unwrap_or(4);
                    let results = self.execute_parallel(step, items_array.clone(), workers, context).await?;

                    Ok(Value::Array(results))
                }

                Action::Sequential { steps } => {
                    let mut last_result = Value::Null;
                    for step in steps {
                        last_result = self.execute_action(&step.action, context).await?;
                        context.set_output(&step.id, last_result.clone());
                    }
                    Ok(last_result)
                }

                Action::Condition { branches, default, .. } => {
                    for branch in branches {
                        if self.evaluate_condition(&branch.when, context)? {
                            return self.execute_action(&branch.then.action, context).await;
                        }
                    }

                    if let Some(default_step) = default {
                        return self.execute_action(&default_step.action, context).await;
                    }

                    Ok(Value::Null)
                }

                Action::Skill { skill_id, input } => {
                    let resolved_input = context.resolve_map(input)?;
                    self.action_registry.execute_skill(skill_id, resolved_input)
                        .await
                        .map_err(|e| ExecuteError::Action(e.to_string()))
                }

                Action::Hand { hand_id, hand_action, params } => {
                    let resolved_params = context.resolve_map(params)?;
                    self.action_registry.execute_hand(hand_id, hand_action, resolved_params)
                        .await
                        .map_err(|e| ExecuteError::Action(e.to_string()))
                }

                Action::ClassroomRender { input } => {
                    let data = context.resolve(input)?;
                    self.action_registry.render_classroom(&data)
                        .await
                        .map_err(|e| ExecuteError::Action(e.to_string()))
                }

                Action::FileExport { formats, input, output_dir } => {
                    let data = context.resolve(input)?;
                    let dir = match output_dir {
                        Some(s) => {
                            let resolved = context.resolve(s)?;
                            resolved.as_str().map(|s| s.to_string())
                        }
                        None => None,
                    };

                    // Resolve formats expression and parse as array
                    let resolved_formats = context.resolve(formats)?;
                    let format_strings: Vec<String> = if resolved_formats.is_array() {
                        resolved_formats.as_array()
                            .ok_or_else(|| ExecuteError::Action("formats must be an array".to_string()))?
                            .iter()
                            .filter_map(|v| v.as_str().map(|s| s.to_string()))
                            .collect()
                    } else if resolved_formats.is_string() {
                        // Try to parse as JSON array string
                        let s = resolved_formats.as_str()
                            .ok_or_else(|| ExecuteError::Action("formats must be a string or array".to_string()))?;
                        serde_json::from_str(s)
                            .unwrap_or_else(|_| vec![s.to_string()])
                    } else {
                        return Err(ExecuteError::Action("formats must be a string or array".to_string()));
                    };

                    // Convert strings to ExportFormat
                    let export_formats: Vec<ExportFormat> = format_strings
                        .iter()
                        .filter_map(|s| match s.to_lowercase().as_str() {
                            "pptx" => Some(ExportFormat::Pptx),
                            "html" => Some(ExportFormat::Html),
                            "pdf" => Some(ExportFormat::Pdf),
                            "markdown" | "md" => Some(ExportFormat::Markdown),
                            "json" => Some(ExportFormat::Json),
                            _ => None,
                        })
                        .collect();

                    self.action_registry.export_files(&export_formats, &data, dir.as_deref())
                        .await
                        .map_err(|e| ExecuteError::Action(e.to_string()))
                }

                Action::HttpRequest { url, method, headers, body } => {
                    let resolved_url = context.resolve(url)?;
                    let url_str = resolved_url.as_str()
                        .ok_or_else(|| ExecuteError::Action("URL must be a string".to_string()))?;

                    let resolved_body = match body {
                        Some(b) => Some(context.resolve(b)?),
                        None => None,
                    };

                    self.action_registry.http_request(
                        url_str,
                        method,
                        headers,
                        resolved_body.as_ref(),
                    ).await
                        .map_err(|e| ExecuteError::Action(e.to_string()))
                }

                Action::SetVar { name, value } => {
                    let resolved = context.resolve(value)?;
                    context.set_var(name, resolved.clone());
                    Ok(resolved)
                }

                Action::Delay { ms } => {
                    tokio::time::sleep(tokio::time::Duration::from_millis(*ms)).await;
                    Ok(Value::Null)
                }

                Action::SkillOrchestration { graph_id, graph, input } => {
                    let resolved_input = context.resolve_map(input)?;
                    self.action_registry.execute_orchestration(
                        graph_id.as_deref(),
                        graph.as_ref(),
                        resolved_input,
                    ).await
                        .map_err(|e| ExecuteError::Action(e.to_string()))
                }
            }
        }.boxed()
    }

    /// Execute parallel steps
    async fn execute_parallel(
        &self,
        step: &PipelineStep,
        items: Vec<Value>,
        max_workers: usize,
        parent_context: &ExecutionContext,
    ) -> Result<Vec<Value>, ExecuteError> {
        let action_registry = self.action_registry.clone();
        let action = step.action.clone();

        // Clone parent context data for child contexts
        let parent_inputs = parent_context.inputs().clone();
        let parent_outputs = parent_context.all_outputs().clone();
        let parent_vars = parent_context.all_vars().clone();

        let results: Vec<Result<Value, ExecuteError>> = stream::iter(items.into_iter().enumerate())
            .map(|(index, item)| {
                let action_registry = action_registry.clone();
                let action = action.clone();
                let parent_inputs = parent_inputs.clone();
                let parent_outputs = parent_outputs.clone();
                let parent_vars = parent_vars.clone();

                async move {
                    // Create child context with parent data and loop variables
                    let mut child_ctx = ExecutionContext::from_parent(
                        parent_inputs,
                        parent_outputs,
                        parent_vars,
                    );
                    child_ctx.set_loop_context(item, index);

                    // Execute the step's action
                    let executor = PipelineExecutor::new(action_registry);
                    executor.execute_action(&action, &mut child_ctx).await
                }
            })
            .buffer_unordered(max_workers)
            .collect()
            .await;

        let mut outputs = Vec::new();
        for result in results {
            outputs.push(result?);
        }

        Ok(outputs)
    }

    /// Evaluate a condition expression
    fn evaluate_condition(&self, condition: &str, context: &ExecutionContext) -> Result<bool, ExecuteError> {
        let resolved = context.resolve(condition)?;

        // If resolved to a boolean, return it
        if let Value::Bool(b) = resolved {
            return Ok(b);
        }

        // Handle string "true" / "false" as boolean values
        if let Value::String(s) = &resolved {
            match s.as_str() {
                "true" => return Ok(true),
                "false" => return Ok(false),
                _ => {}
            }
        }

        // Check for comparison operators
        let condition = condition.trim();

        // Equality check
        if let Some(eq_pos) = condition.find("==") {
            let left = condition[..eq_pos].trim();
            let right = condition[eq_pos + 2..].trim();

            let left_val = context.resolve(left)?;
            // Handle quoted string literals for right side
            let right_val = if right.starts_with('\'') && right.ends_with('\'') {
                // Remove quotes and return as string value
                Value::String(right[1..right.len()-1].to_string())
            } else if right.starts_with('"') && right.ends_with('"') {
                // Remove double quotes and return as string value
                Value::String(right[1..right.len()-1].to_string())
            } else {
                context.resolve(right)?
            };

            return Ok(left_val == right_val);
        }

        // Inequality check
        if let Some(ne_pos) = condition.find("!=") {
            let left = condition[..ne_pos].trim();
            let right = condition[ne_pos + 2..].trim();

            let left_val = context.resolve(left)?;
            let right_val = context.resolve(right)?;

            return Ok(left_val != right_val);
        }

        // Default: treat as truthy check
        Ok(!resolved.is_null())
    }

    /// Get run status
    pub async fn get_run(&self, run_id: &str) -> Option<PipelineRun> {
        self.runs.read().await.get(run_id).cloned()
    }

    /// Get run progress
    pub async fn get_progress(&self, run_id: &str) -> Option<PipelineProgress> {
        let run = self.runs.read().await.get(run_id)?.clone();

        let (current_step, percentage) = if run.step_results.is_empty() {
            ("starting".to_string(), 0)
        } else if let Some(step) = &run.current_step {
            (step.clone(), 50)
        } else {
            ("completed".to_string(), 100)
        };

        Some(PipelineProgress {
            run_id: run.id,
            current_step,
            message: run.current_step.clone().unwrap_or_default(),
            percentage,
            status: run.status,
        })
    }

    /// Cancel a run
    pub async fn cancel(&self, run_id: &str) {
        self.cancellations.write().await.insert(run_id.to_string(), true);
    }

    /// List all runs
    pub async fn list_runs(&self) -> Vec<PipelineRun> {
        self.runs.read().await.values().cloned().collect()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde_json::json;

    #[test]
    fn test_evaluate_condition_bool() {
        let registry = Arc::new(ActionRegistry::new());
        let executor = PipelineExecutor::new(registry);
        let ctx = ExecutionContext::new(HashMap::new());

        assert!(executor.evaluate_condition("true", &ctx).unwrap());
        assert!(!executor.evaluate_condition("false", &ctx).unwrap());
    }

    #[test]
    fn test_evaluate_condition_equality() {
        let registry = Arc::new(ActionRegistry::new());
        let executor = PipelineExecutor::new(registry);
        let ctx = ExecutionContext::new(
            vec![("type".to_string(), json!("video"))]
                .into_iter()
                .collect()
        );

        assert!(executor.evaluate_condition("${inputs.type} == 'video'", &ctx).unwrap());
        assert!(!executor.evaluate_condition("${inputs.type} == 'text'", &ctx).unwrap());
    }
}