// SPF Smart Gateway - Gate (Primary Enforcement Point)
// Copyright 2026 Joseph Stone - All Rights Reserved
//
// Every tool call passes through here. Calculate -> Validate -> Allow/Warn.
// Max mode: violations warn + force CRITICAL tier. Never blocks — escalates.
// Enforcement: compiled validation rules, write whitelist, path blocking,
// Build Anchor protocol, content inspection. No runtime config bypass.
//
// REFACTOR: Source-aware gate — source: &Source added to process().
//   gate::process() is the SINGLE ENTRY POINT. Called before handle_tool_call
//   on every path (stdio, dispatch, FLINT). No gate calls inside match arms.
//   Source::Transformer (FLINT) — same permissions as Stdio. Full tool access.

use chrono::Utc;
use crate::calculate::{self, ComplexityResult, ToolParams};
use crate::config::{EnforceMode, SpfConfig};
use crate::dispatch::Source;
use crate::inspect;
use crate::session::Session;
use crate::validate;
use serde::{Deserialize, Serialize};

/// Gate decision — the final word on whether a tool call proceeds
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct GateDecision {
    pub allowed: bool,
    pub tool: String,
    pub complexity: ComplexityResult,
    pub warnings: Vec<String>,
    pub errors: Vec<String>,
    pub message: String,
}

/// Human-readable summary of what the action will do.
fn format_params(tool: &str, params: &ToolParams) -> String {
    match tool {
        "Bash" | "spf_bash" => {
            format!("Command: {}", params.command.as_deref().unwrap_or("(none)"))
        }
        "Read" | "spf_read" => {
            format!("File: {}", params.file_path.as_deref().unwrap_or("(none)"))
        }
        "Write" | "spf_write" => {
            let len = params.content.as_ref().map(|c| c.len()).unwrap_or(0);
            format!("File: {} | Content: {} bytes",
                params.file_path.as_deref().unwrap_or("(none)"), len)
        }
        "Edit" | "spf_edit" => {
            let old_preview: String = params.old_string.as_deref()
                .unwrap_or("").chars().take(60).collect();
            let new_preview: String = params.new_string.as_deref()
                .unwrap_or("").chars().take(60).collect();
            format!("File: {} | Replace: \"{}...\" -> \"{}...\"",
                params.file_path.as_deref().unwrap_or("(none)"),
                old_preview, new_preview)
        }
        "Glob" | "spf_glob" => {
            format!("Pattern: {} | Path: {}",
                params.command.as_deref().unwrap_or("*"),
                params.file_path.as_deref().unwrap_or("."))
        }
        "Grep" | "spf_grep" => {
            format!("Pattern: {} | Path: {}",
                params.command.as_deref().unwrap_or(""),
                params.file_path.as_deref().unwrap_or("."))
        }
        _ => {
            let mut parts = Vec::new();
            if let Some(ref cmd) = params.command {
                parts.push(format!("arg: {}", cmd));
            }
            if let Some(ref fp) = params.file_path {
                parts.push(format!("path: {}", fp));
            }
            if parts.is_empty() { "(no params)".to_string() } else { parts.join(" | ") }
        }
    }
}

// ============================================================================
// GATE PROCESS — single entry point for all tool calls
// ============================================================================

/// Process a tool call through the gate.
/// Called BEFORE handle_tool_call on every path — gate is the door.
///
/// Pipeline:
/// 0. Source logging — who is calling? (logged, not blocked)
/// 1. Rate limiting
/// 2. Calculate complexity (C, tier, allocation)
/// 3. Validate against rules (blocked paths, Build Anchor, write whitelist)
/// 4. Content inspection on Write/Edit
/// 5. Max mode escalation
/// 6. Return allow/block decision
pub fn process(
    tool: &str,
    params: &ToolParams,
    config: &SpfConfig,
    session: &Session,
    source: &Source,
) -> GateDecision {

    // ── STEP 0: SOURCE LOGGING ────────────────────────────────────────────────
    // Log source identity for training pipeline. FLINT has full tool access —
    // same permissions as Stdio. All calls still pass through validation below.
    if let Source::Transformer { ref role, ref model_id } = source {
        eprintln!("[GATE] Source::Transformer role={} model={} tool={}", role, model_id, tool);
    }

    // ── STEP 1: RATE LIMITING ────────────────────────────────────────────────
    let now = Utc::now();
    let one_minute_ago = now - chrono::Duration::seconds(60);
    let recent_count = session.rate_window.iter()
        .filter(|ts| **ts > one_minute_ago)
        .count();

    let max_per_minute = match tool {
        "Write" | "spf_write" | "Edit" | "spf_edit" |
        "Bash" | "spf_bash" | "spf_web_download" | "spf_notebook_edit" => 60,
        "spf_web_fetch" | "spf_web_search" | "spf_web_api" => 30,
        "spf_web_connect" | "spf_web_navigate" => 20,
        "spf_web_click" | "spf_web_fill" | "spf_web_select" |
        "spf_web_eval" | "spf_web_screenshot" | "spf_web_design" | "spf_web_page" => 60,
        "spf_mesh_call" => 60,
        _ => 120,
    };

    if recent_count >= max_per_minute {
        let msg = format!("RATE LIMITED: {} calls in last minute (max {})", recent_count, max_per_minute);
        return GateDecision {
            allowed: false,
            tool: tool.to_string(),
            complexity: ComplexityResult {
                tool: tool.to_string(),
                c: 0,
                tier: "RATE_LIMITED".to_string(),
                analyze_percent: 100,
                build_percent: 0,
                a_optimal_tokens: 0,
                requires_approval: true,
            },
            warnings: vec![],
            errors: vec![msg.clone()],
            message: format!("BLOCKED | {} | {}", tool, msg),
        };
    }

    // ── STEP 2: CALCULATE COMPLEXITY ────────────────────────────────────────
    let mut complexity = calculate::calculate(tool, params, config);
    let mut warnings = Vec::new();
    let mut errors = Vec::new();

    // ── STEP 3: VALIDATE AGAINST RULES ──────────────────────────────────────
    let validation = match tool {
        "Edit" | "spf_edit" => {
            let file_path = params.file_path.as_deref().unwrap_or("unknown");
            validate::validate_edit(file_path, config, session)
        }
        "Write" | "spf_write" => {
            let file_path = params.file_path.as_deref().unwrap_or("unknown");
            let content_len = params.content.as_ref().map(|c| c.len()).unwrap_or(0);
            validate::validate_write(file_path, content_len, config, session)
        }
        "Bash" | "spf_bash" => {
            let command = params.command.as_deref().unwrap_or("");
            validate::validate_bash(command, config, Some(session))
        }
        "Read" | "spf_read" => {
            let file_path = params.file_path.as_deref().unwrap_or("unknown");
            validate::validate_read(file_path, config)
        }
        "spf_web_download" => {
            // Check source URL first (SSRF guard), then validate save path
            let url_result = validate::validate_url(params, config);
            if !url_result.valid {
                url_result
            } else {
                let file_path = params.file_path.as_deref().unwrap_or("unknown");
                validate::validate_write(file_path, 0, config, session)
            }
        }
        "spf_notebook_edit" => {
            let file_path = params.file_path.as_deref().unwrap_or("unknown");
            let content_len = params.content.as_ref().map(|c| c.len()).unwrap_or(0);
            validate::validate_write(file_path, content_len, config, session)
        }
        // HARD BLOCK — spf_fs_* tools are USER/SYSTEM-ONLY, never via AI
        "spf_fs_import" | "spf_fs_export" |
        "spf_fs_exists" | "spf_fs_stat" | "spf_fs_ls" | "spf_fs_read" |
        "spf_fs_write" | "spf_fs_mkdir" | "spf_fs_rm" | "spf_fs_rename" => {
            validate::ValidationResult {
                valid: false,
                warnings: vec![],
                errors: vec![format!("BLOCKED: {} is a user/system-only command — not available to AI agents", tool)],
            }
        }
        // ── TIER A — Filesystem reads (path traversal + sensitive prefix) ─────
        "Glob" | "spf_glob" |
        "Grep" | "spf_grep" |
        "spf_rag_collect_file" | "spf_rag_collect_folder"
            => validate::validate_fs_read(params, config),

        // ── TIER B — Web/URL (scheme + SSRF check) ────────────────────────────
        "spf_web_fetch" | "spf_web_api" | "spf_web_navigate"
            => validate::validate_url(params, config),

        // ── TIER B+ — RAG content (URL + length + injection) ──────────────────
        "spf_rag_collect_web" | "spf_rag_fetch_url"
            => validate::validate_rag_content(params, config),

        // ── TIER C — Controlled delegation ────────────────────────────────────
        "spf_flint_execute"
            => validate::validate_flint_execute(params, config),
        "spf_mesh_call"
            => validate::validate_mesh_call(params, config),

        // ── TIER D — Bounded inference ─────────────────────────────────────────
        "spf_transformer_infer" | "spf_transformer_chat" | "spf_transformer_train"
        | "spf_flint_train_evil" | "spf_flint_train_good"
        | "spf_flint_store"
            => validate::validate_transformer_ops(params, config),

        // ── TIER E+ — Brain write (source-gated) ────────────────────────────
        // FLINT router thread writes brain via direct calls (bypasses gate).
        // Only MCP Source::Stdio reaches here — block agent brain writes.
        "spf_brain_store" | "spf_brain_index" => {
            match source {
                Source::Stdio => validate::ValidationResult::block(
                    "BRAIN-WRITE: brain_store/brain_index blocked from agent (Source::Stdio). \
                     FLINT owns brain writes. Use brain_search/brain_recall to read.".to_string()
                ),
                _ => validate::ValidationResult::ok(),
            }
        },

        // ── TIER E — Safe read-only (no mutation risk) ────────────────────────
        "spf_calculate" | "spf_status" | "spf_session" |
        "spf_web_search" |
        "spf_brain_search" | "spf_brain_context" |
        "spf_brain_list" | "spf_brain_status" |
        "spf_brain_recall" | "spf_brain_list_docs" | "spf_brain_get_doc" |
        "spf_rag_collect_drop" | "spf_rag_index_gathered" | "spf_rag_dedupe" |
        "spf_rag_status" | "spf_rag_list_gathered" | "spf_rag_bandwidth_status" |
        "spf_rag_collect_rss" | "spf_rag_list_feeds" |
        "spf_rag_pending_searches" | "spf_rag_fulfill_search" |
        "spf_rag_smart_search" | "spf_rag_auto_fetch_gaps" |
        "spf_config_paths" | "spf_config_stats" |
        "spf_projects_list" | "spf_projects_get" | "spf_projects_set" |
        "spf_projects_delete" | "spf_projects_stats" |
        "spf_tmp_list" | "spf_tmp_stats" | "spf_tmp_get" | "spf_tmp_active" |
        "spf_agent_stats" | "spf_agent_memory_search" | "spf_agent_memory_by_tag" |
        "spf_agent_session_info" | "spf_agent_context" |
        "spf_web_connect" | "spf_web_click" | "spf_web_fill" | "spf_web_select" |
        "spf_web_eval" | "spf_web_screenshot" | "spf_web_design" | "spf_web_page" |
        "spf_mesh_status" | "spf_mesh_peers" |
        "spf_transformer_status" | "spf_transformer_metrics" |
        "spf_voice_mode" | "spf_voice_call" | "spf_voice_team" |
        "spf_chat_send" | "spf_chat_receive" | "spf_chat_history" | "spf_chat_rooms" |
        "spf_pool_status" | "spf_pool_assign" | "spf_pool_release" |
        "spf_channel"
            => validate::ValidationResult::ok(),
        // DEFAULT DENY — unknown tools blocked until explicitly added
        _ => {
            validate::ValidationResult {
                valid: false,
                warnings: vec![],
                errors: vec![format!("BLOCKED: unknown tool '{}' — not in gate allowlist", tool)],
            }
        }
    };

    warnings.extend(validation.warnings);
    errors.extend(validation.errors);

    // ── STEP 4: CONTENT INSPECTION ───────────────────────────────────────────
    let inspection = match tool {
        "Write" | "spf_write" => {
            let file_path = params.file_path.as_deref().unwrap_or("unknown");
            let content = params.content.as_deref().unwrap_or("");
            inspect::inspect_content(content, file_path, config)
        }
        "Edit" | "spf_edit" => {
            let file_path = params.file_path.as_deref().unwrap_or("unknown");
            let new_string = params.new_string.as_deref().unwrap_or("");
            inspect::inspect_content(new_string, file_path, config)
        }
        "spf_notebook_edit" => {
            let file_path = params.file_path.as_deref().unwrap_or("unknown");
            let content = params.content.as_deref().unwrap_or("");
            inspect::inspect_content(content, file_path, config)
        }
        "spf_flint_store" => {
            let content = params.text.as_deref().unwrap_or("");
            inspect::inspect_content(content, "brain_store:text", config)
        }
        _ => validate::ValidationResult::ok(),
    };

    warnings.extend(inspection.warnings);
    errors.extend(inspection.errors);

    // ── STEP 5: MAX MODE ESCALATION ──────────────────────────────────────────
    if config.enforce_mode == EnforceMode::Max {
        let has_max_warnings = warnings.iter().any(|w| w.starts_with("MAX TIER:"));
        if has_max_warnings {
            complexity.tier = "CRITICAL".to_string();
            complexity.analyze_percent = config.tiers.critical.analyze_percent;
            complexity.build_percent = config.tiers.critical.build_percent;
            complexity.requires_approval = true;
            warnings.push("ESCALATED TO CRITICAL TIER — Max mode enforcement".to_string());
        }
    }

    let allowed = validation.valid && inspection.valid;
    let details = format_params(tool, params);
    let message = if allowed {
        format!("ALLOWED | {} | C={} | {} | {}%/{}% | {}",
            tool, complexity.c, complexity.tier,
            complexity.analyze_percent, complexity.build_percent, details)
    } else {
        format!("BLOCKED | {} | C={} | {} errors | {}",
            tool, complexity.c, errors.len(), details)
    };

    GateDecision { allowed, tool: tool.to_string(), complexity, warnings, errors, message }
}

// ============================================================================
// TESTS
// ============================================================================

#[cfg(test)]
mod tests {
    use super::*;
    use crate::config::SpfConfig;
    use crate::session::Session;

    fn default_config() -> SpfConfig { SpfConfig::default() }
    fn stdio() -> Source { Source::Stdio }
    fn transformer() -> Source {
        Source::Transformer { role: "worker".to_string(), model_id: "flint".to_string() }
    }

    #[test]
    fn allowed_tool_passes_gate() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams::default();
        let decision = process("spf_status", &params, &config, &session, &stdio());
        assert!(decision.allowed, "spf_status should be allowed: {}", decision.message);
    }

    #[test]
    fn blocked_fs_tool_denied() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams::default();
        let decision = process("spf_fs_write", &params, &config, &session, &stdio());
        assert!(!decision.allowed, "spf_fs_write should be BLOCKED");
        assert!(decision.errors.iter().any(|e| e.contains("BLOCKED")));
    }

    #[test]
    fn unknown_tool_denied_default_deny() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams::default();
        let decision = process("evil_new_tool", &params, &config, &session, &stdio());
        assert!(!decision.allowed, "Unknown tool should be blocked by default-deny");
        assert!(decision.errors.iter().any(|e| e.contains("not in gate allowlist")));
    }

    #[test]
    fn all_fs_tools_blocked() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams::default();
        let fs_tools = [
            "spf_fs_exists", "spf_fs_stat", "spf_fs_ls", "spf_fs_read",
            "spf_fs_write", "spf_fs_mkdir", "spf_fs_rm", "spf_fs_rename",
        ];
        for tool in &fs_tools {
            let decision = process(tool, &params, &config, &session, &stdio());
            assert!(!decision.allowed, "{} should be BLOCKED", tool);
        }
    }

    #[test]
    fn mesh_read_tools_allowed_through_gate() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams::default();
        for tool in &["spf_mesh_status", "spf_mesh_peers"] {
            let decision = process(tool, &params, &config, &session, &stdio());
            assert!(decision.allowed, "{} should be ALLOWED: {}", tool, decision.message);
        }
    }

    #[test]
    fn mesh_call_blocked_without_peer_key() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams::default(); // peer_key = None
        let decision = process("spf_mesh_call", &params, &config, &session, &stdio());
        assert!(!decision.allowed, "spf_mesh_call with no peer_key must be BLOCKED");
        assert!(decision.errors.iter().any(|e| e.contains("MESH")));
    }

    #[test]
    fn mesh_call_allowed_with_valid_peer_key() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams {
            peer_key: Some("4c327f6d8dfa032873dcf4355b44ae412174f880e720d5bd0b2babbf0dbc33f3".to_string()),
            command: Some("spf_brain_search".to_string()),
            ..Default::default()
        };
        let decision = process("spf_mesh_call", &params, &config, &session, &stdio());
        assert!(decision.allowed, "spf_mesh_call with valid peer_key+tool must be ALLOWED: {}", decision.message);
    }

    #[test]
    fn voice_chat_tools_allowed_through_gate() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams::default();
        let tools = [
            "spf_voice_mode", "spf_voice_call", "spf_voice_team",
            "spf_chat_send", "spf_chat_receive",
            "spf_chat_history", "spf_chat_rooms",
        ];
        for tool in &tools {
            let decision = process(tool, &params, &config, &session, &stdio());
            assert!(decision.allowed, "{} should be ALLOWED: {}", tool, decision.message);
        }
    }

    #[test]
    fn flint_execute_blocked_without_tool_name() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams::default(); // tool_name = None
        let decision = process("spf_flint_execute", &params, &config, &session, &stdio());
        assert!(!decision.allowed, "flint_execute with no tool_name must be BLOCKED");
        assert!(decision.errors.iter().any(|e| e.contains("FLINT")));
    }

    #[test]
    fn flint_execute_allowed_with_valid_params() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams {
            tool_name: Some("spf_brain_search".to_string()),
            reason: Some("Searching for relevant project context".to_string()),
            ..Default::default()
        };
        let decision = process("spf_flint_execute", &params, &config, &session, &stdio());
        assert!(decision.allowed, "flint_execute with valid tool_name+reason must be ALLOWED: {}", decision.message);
    }

    #[test]
    fn flint_execute_allowed_for_write_delegation() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams {
            tool_name: Some("spf_write".to_string()),
            reason: Some("Writing a file via FLINT".to_string()),
            ..Default::default()
        };
        let decision = process("spf_flint_execute", &params, &config, &session, &stdio());
        assert!(decision.allowed, "flint_execute should delegate to spf_write: {}", decision.message);
    }

    #[test]
    fn transformer_has_same_permissions_as_stdio() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams::default();
        // FLINT gets identical gate treatment to Stdio — no source-based blocking.
        // Both still subject to path validation, rate limiting, etc.
        let read_tools = ["spf_status", "spf_brain_search", "spf_mesh_status"];
        for tool in &read_tools {
            let stdio_decision = process(tool, &params, &config, &session, &stdio());
            let flint_decision = process(tool, &params, &config, &session, &transformer());
            assert_eq!(stdio_decision.allowed, flint_decision.allowed,
                "FLINT and Stdio should have same result for {}", tool);
        }
    }

    #[test]
    fn transformer_can_read() {
        let config = default_config();
        let session = Session::new();
        let params = ToolParams::default();
        let decision = process("spf_status", &params, &config, &session, &transformer());
        assert!(decision.allowed, "Transformer should be able to call spf_status");
    }
}