//! Simplified interactive theorem prover

use anyhow::Result;

use serde::{Deserialize, Serialize};

use std::collections::HashMap;

use super::smt::SmtBackend;

use super::tactics::TacticLibrary;

/// Interactive prover

pub struct InteractiveProver {

    _backend: SmtBackend,

    tactics: TacticLibrary,

    timeout: u64,

    ml_suggestions: bool,

}

impl InteractiveProver {

    /// Create new prover

    pub fn new(backend: SmtBackend) -> Self {

        Self {

            _backend: backend,

            tactics: TacticLibrary::default(),

            timeout: 5000,

            ml_suggestions: false,

        }

    }

    /// Set timeout

    pub fn set_timeout(&mut self, timeout: u64) {

        self.timeout = timeout;

    }

    /// Enable ML suggestions

    pub fn set_ml_suggestions(&mut self, enabled: bool) {

        self.ml_suggestions = enabled;

    }

    /// Load proof script

    pub fn load_script(&mut self, _script: &str) -> Result<()> {

        // Simplified: just return ok

        Ok(())

    }

    /// Get available tactics

    pub fn get_available_tactics(&self) -> Vec<&dyn super::tactics::Tactic> {

        self.tactics.all_tactics()

    }

    /// Apply tactic

    pub fn apply_tactic(&mut self, session: &mut ProverSession, tactic_name: &str, args: &[&str]) -> Result<ProofResult> {

        let tactic = self.tactics.get_tactic(tactic_name)?;

        if let Some(goal) = session.current_goal() {

            let result = tactic.apply(goal, args, &session.context)?;

            match result {

                StepResult::Solved => {

                    session.complete_goal();

                    Ok(ProofResult::Solved)

                }

                StepResult::Simplified(new_goal) => {

                    session.update_goal(new_goal);

                    Ok(ProofResult::Progress)

                }

                StepResult::Subgoals(subgoals) => {

                    session.replace_with_subgoals(subgoals);

                    Ok(ProofResult::Progress)

                }

                StepResult::Failed(msg) => {

                    Ok(ProofResult::Failed(msg))

                }

            }

        } else {

            Ok(ProofResult::Failed("No active goal".to_string()))

        }

    }

    /// Process input

    pub fn process_input(&mut self, session: &mut ProverSession, input: &str) -> Result<ProofResult> {

        // Try to parse as goal

        if let Some(goal) = input.strip_prefix("prove ") {

            session.add_goal(goal.to_string());

            return Ok(ProofResult::Progress);

        }

        // Try as tactic

        let parts: Vec<&str> = input.split_whitespace().collect();

        if !parts.is_empty() {

            let tactic_name = parts[0];

            let args = &parts[1..];

            return self.apply_tactic(session, tactic_name, args);

        }

        Ok(ProofResult::Failed("Unknown command".to_string()))

    }

    /// Suggest tactics

    pub fn suggest_tactics(&self, goal: &ProofGoal) -> Result<Vec<super::tactics::TacticSuggestion>> {

        self.tactics.suggest_tactics(goal, &ProofContext::new())

    }

}

/// Prover session

#[derive(Debug, Clone, Serialize, Deserialize)]

pub struct ProverSession {

    goals: Vec<ProofGoal>,

    context: ProofContext,

    history: Vec<String>,

}

impl ProverSession {

    /// Create new session

    pub fn new() -> Self {

        Self {

            goals: Vec::new(),

            context: ProofContext::new(),

            history: Vec::new(),

        }

    }

    /// Add goal

    pub fn add_goal(&mut self, statement: String) {

        self.goals.push(ProofGoal { statement });

    }

    /// Get current goal

    pub fn current_goal(&self) -> Option<&ProofGoal> {

        self.goals.first()

    }

    /// Update current goal

    pub fn update_goal(&mut self, statement: String) {

        if !self.goals.is_empty() {

            self.goals[0].statement = statement;

        }

    }

    /// Complete current goal

    pub fn complete_goal(&mut self) {

        if !self.goals.is_empty() {

            self.goals.remove(0);

        }

    }

    /// Replace with subgoals

    pub fn replace_with_subgoals(&mut self, subgoals: Vec<String>) {

        if !self.goals.is_empty() {

            self.goals.remove(0);

            for subgoal in subgoals.into_iter().rev() {

                self.goals.insert(0, ProofGoal { statement: subgoal });

            }

        }

    }

    /// Get all goals

    pub fn get_goals(&self) -> &[ProofGoal] {

        &self.goals

    }

    /// Check if complete

    pub fn is_complete(&self) -> bool {

        self.goals.is_empty()

    }

    /// Export to text

    pub fn to_text_proof(&self) -> String {

        let mut proof = String::new();

        proof.push_str("Proof:\n");

        for line in &self.history {

            use std::fmt::Write;

            let _ = writeln!(proof, "  {line}");

        }

        if self.is_complete() {

            proof.push_str("Qed.\n");

        }

        proof

    }

    /// Export to Coq

    pub fn to_coq_proof(&self) -> String {

        self.to_text_proof() // Simplified

    }

    /// Export to Lean

    pub fn to_lean_proof(&self) -> String {

        self.to_text_proof() // Simplified

    }

}

impl Default for ProverSession {

    fn default() -> Self {

        Self::new()

    }

}

/// Proof goal

#[derive(Debug, Clone, Serialize, Deserialize)]

pub struct ProofGoal {

    pub statement: String,

}

/// Proof context

#[derive(Debug, Clone, Serialize, Deserialize)]

pub struct ProofContext {

    pub assumptions: Vec<String>,

    pub definitions: HashMap<String, String>,

}

impl ProofContext {

    /// Create new context

    pub fn new() -> Self {

        Self {

            assumptions: Vec::new(),

            definitions: HashMap::new(),

        }

    }

}

impl Default for ProofContext {

    fn default() -> Self {

        Self::new()

    }

}

/// Proof result

#[derive(Debug)]

pub enum ProofResult {

    Solved,

    Progress,

    Failed(String),

}

/// Step result from tactic application

#[derive(Debug, Clone)]

pub enum StepResult {

    /// Goal was solved

    Solved,

    /// Goal was simplified to new goal

    Simplified(String),

    /// Goal was split into subgoals

    Subgoals(Vec<String>),

    /// Tactic failed

    Failed(String),

}

#[cfg(test)]

mod tests {

    use super::*;

    use crate::proving::smt::SmtBackend;

    fn create_test_prover() -> InteractiveProver {

        let backend = SmtBackend::Z3;

        InteractiveProver::new(backend)

    }

    fn create_test_session() -> ProverSession {

        ProverSession::new()

    }

    // Test 1: Prover Creation and Basic Configuration

    #[test]

    fn test_prover_creation() {

        let prover = create_test_prover();

        assert_eq!(prover.timeout, 5000);

        assert!(!prover.ml_suggestions);

    }

    #[test]

    fn test_prover_timeout_setting() {

        let mut prover = create_test_prover();

        prover.set_timeout(10000);

        assert_eq!(prover.timeout, 10000);

    }

    #[test]

    fn test_prover_ml_suggestions_setting() {

        let mut prover = create_test_prover();

        prover.set_ml_suggestions(true);

        assert!(prover.ml_suggestions);

        prover.set_ml_suggestions(false);

        assert!(!prover.ml_suggestions);

    }

    #[test]

    fn test_prover_load_script() {

        let mut prover = create_test_prover();

        let result = prover.load_script("example script");

        assert!(result.is_ok());

    }

    // Test 2: Session Management

    #[test]

    fn test_session_creation() {

        let session = create_test_session();

        assert!(session.goals.is_empty());

        assert!(session.history.is_empty());

        assert!(session.is_complete());

    }

    #[test]

    fn test_session_default() {

        let session = ProverSession::default();

        assert!(session.goals.is_empty());

        assert!(session.is_complete());

    }

    #[test]

    fn test_session_add_goal() {

        let mut session = create_test_session();

        session.add_goal("forall x, x = x".to_string());

        assert_eq!(session.goals.len(), 1);

        assert!(!session.is_complete());

        let current_goal = session.current_goal().unwrap();

        assert_eq!(current_goal.statement, "forall x, x = x");

    }

    #[test]

    fn test_session_multiple_goals() {

        let mut session = create_test_session();

        session.add_goal("goal1".to_string());

        session.add_goal("goal2".to_string());

        assert_eq!(session.goals.len(), 2);

        let current = session.current_goal().unwrap();

        assert_eq!(current.statement, "goal1");

    }

    #[test]

    fn test_session_complete_goal() {

        let mut session = create_test_session();

        session.add_goal("test goal".to_string());

        assert!(!session.is_complete());

        session.complete_goal();

        assert!(session.is_complete());

    }

    #[test]

    fn test_session_update_goal() {

        let mut session = create_test_session();

        session.add_goal("original goal".to_string());

        session.update_goal("updated goal".to_string());

        let current = session.current_goal().unwrap();

        assert_eq!(current.statement, "updated goal");

    }

    #[test]

    fn test_session_replace_with_subgoals() {

        let mut session = create_test_session();

        session.add_goal("main goal".to_string());

        let subgoals = vec!["subgoal1".to_string(), "subgoal2".to_string()];

        session.replace_with_subgoals(subgoals);

        assert_eq!(session.goals.len(), 2);

        // Due to .rev() then inserting at position 0, order is preserved

        assert_eq!(session.goals[0].statement, "subgoal1"); 

        assert_eq!(session.goals[1].statement, "subgoal2");

    }

    // Test 3: Goal Operations

    #[test]

    fn test_get_goals() {

        let mut session = create_test_session();

        session.add_goal("goal1".to_string());

        session.add_goal("goal2".to_string());

        let goals = session.get_goals();

        assert_eq!(goals.len(), 2);

        assert_eq!(goals[0].statement, "goal1");

        assert_eq!(goals[1].statement, "goal2");

    }

    #[test]

    fn test_session_completion_status() {

        let mut session = create_test_session();

        assert!(session.is_complete());

        session.add_goal("test".to_string());

        assert!(!session.is_complete());

        session.complete_goal();

        assert!(session.is_complete());

    }

    // Test 4: Text Export Features

    #[test]

    fn test_text_proof_export_empty() {

        let session = create_test_session();

        let text_proof = session.to_text_proof();

        assert!(text_proof.contains("Proof:"));

        assert!(text_proof.contains("Qed."));

    }

    #[test]

    fn test_text_proof_export_with_history() {

        let mut session = create_test_session();

        session.history.push("apply reflexivity".to_string());

        session.history.push("exact H".to_string());

        let text_proof = session.to_text_proof();

        assert!(text_proof.contains("apply reflexivity"));

        assert!(text_proof.contains("exact H"));

        assert!(text_proof.contains("Qed."));

    }

    #[test]

    fn test_text_proof_export_incomplete() {

        let mut session = create_test_session();

        session.add_goal("incomplete goal".to_string());

        session.history.push("started proof".to_string());

        let text_proof = session.to_text_proof();

        assert!(text_proof.contains("started proof"));

        assert!(!text_proof.contains("Qed.")); // Should not have Qed for incomplete proof

    }

    #[test]

    fn test_coq_proof_export() {

        let session = create_test_session();

        let coq_proof = session.to_coq_proof();

        // Currently simplified to text proof

        assert!(coq_proof.contains("Proof:"));

        assert!(coq_proof.contains("Qed."));

    }

    #[test]

    fn test_lean_proof_export() {

        let session = create_test_session();

        let lean_proof = session.to_lean_proof();

        // Currently simplified to text proof

        assert!(lean_proof.contains("Proof:"));

        assert!(lean_proof.contains("Qed."));

    }

    // Test 5: Input Processing

    #[test]

    fn test_process_prove_command() {

        let mut prover = create_test_prover();

        let mut session = create_test_session();

        let result = prover.process_input(&mut session, "prove forall x, x = x").unwrap();

        match result {

            ProofResult::Progress => {

                assert_eq!(session.goals.len(), 1);

                assert_eq!(session.current_goal().unwrap().statement, "forall x, x = x");

            }

            _ => panic!("Expected Progress result"),

        }

    }

    #[test]

    fn test_process_empty_input() {

        let mut prover = create_test_prover();

        let mut session = create_test_session();

        let result = prover.process_input(&mut session, "").unwrap();

        match result {

            ProofResult::Failed(msg) => {

                assert!(msg.contains("Unknown command"));

            }

            _ => panic!("Expected Failed result"),

        }

    }

    #[test]

    fn test_process_unknown_command() {

        let mut prover = create_test_prover();

        let mut session = create_test_session();

        let result = prover.process_input(&mut session, "unknown_command arg1 arg2");

        // Should try to apply as tactic and fail with error

        match result {

            Err(e) => {

                assert!(e.to_string().contains("Unknown tactic"));

            }

            Ok(ProofResult::Failed(_)) => {

                // This is also acceptable

            }

            _ => panic!("Expected error or Failed result"),

        }

    }

    // Test 6: Proof Context

    #[test]

    fn test_proof_context_creation() {

        let context = ProofContext::new();

        assert!(context.assumptions.is_empty());

        assert!(context.definitions.is_empty());

    }

    #[test]

    fn test_proof_context_default() {

        let context = ProofContext::default();

        assert!(context.assumptions.is_empty());

        assert!(context.definitions.is_empty());

    }

    // Test 7: Proof Goal Structure

    #[test]

    fn test_proof_goal_creation() {

        let goal = ProofGoal {

            statement: "test statement".to_string(),

        };

        assert_eq!(goal.statement, "test statement");

    }

    // Test 8: Edge Cases

    #[test]

    fn test_complete_goal_empty_session() {

        let mut session = create_test_session();

        session.complete_goal(); // Should not panic

        assert!(session.is_complete());

    }

    #[test]

    fn test_update_goal_empty_session() {

        let mut session = create_test_session();

        session.update_goal("new goal".to_string()); // Should not panic

        assert!(session.is_complete());

    }

    #[test]

    fn test_replace_subgoals_empty_session() {

        let mut session = create_test_session();

        session.replace_with_subgoals(vec!["goal1".to_string()]); // Should not panic

        assert!(session.is_complete());

    }

    #[test]

    fn test_current_goal_empty_session() {

        let session = create_test_session();

        assert!(session.current_goal().is_none());

    }

    // Test 9: Serialization (Basic Structure Test)

    #[test]

    fn test_session_serialization_structure() {

        let mut session = create_test_session();

        session.add_goal("test goal".to_string());

        session.context.assumptions.push("assumption1".to_string());

        session.history.push("step1".to_string());

        // Test that all fields are accessible for serialization

        assert_eq!(session.goals.len(), 1);

        assert_eq!(session.context.assumptions.len(), 1);

        assert_eq!(session.history.len(), 1);

    }

    // Test 10: Multiple Session Operations

    #[test]

    fn test_complex_session_workflow() {

        let mut session = create_test_session();

        // Add initial goal

        session.add_goal("main theorem".to_string());

        assert_eq!(session.goals.len(), 1);

        // Replace with subgoals

        session.replace_with_subgoals(vec![

            "subgoal 1".to_string(),

            "subgoal 2".to_string(),

            "subgoal 3".to_string(),

        ]);

        assert_eq!(session.goals.len(), 3);

        // Complete first subgoal

        session.complete_goal();

        assert_eq!(session.goals.len(), 2);

        // Update current goal

        session.update_goal("modified subgoal".to_string());

        assert_eq!(session.current_goal().unwrap().statement, "modified subgoal");

        // Complete remaining goals

        session.complete_goal();

        session.complete_goal();

        assert!(session.is_complete());

    }

}