#define CATCH_CONFIG_MAIN
#include "catch2/catch.hpp"
#include "Arduino.h"
#include "painlessmesh/mesh.hpp"

using namespace painlessmesh;

// Declare logger for test environment
painlessmesh::logger::LogClass Log;

SCENARIO("Channel re-detection threshold is configured correctly") {
    GIVEN("The StationScan empty scan threshold") {
        WHEN("Checking the threshold constant") {
            // The threshold should be set to trigger re-scan after reasonable period
            // At default SCAN_INTERVAL (30 seconds), 6 scans = ~3 minutes total
            // This is conservative enough to avoid false triggers but responsive enough
            // to handle channel changes from bridge promotion
            const uint16_t EMPTY_SCAN_THRESHOLD = 6;
            
            THEN("Threshold should be 6 scans") {
                REQUIRE(EMPTY_SCAN_THRESHOLD == 6);
            }
            
            THEN("Threshold results in ~30 seconds delay") {
                // SCAN_INTERVAL is 30 seconds by default
                // With fast scanning (0.5 * SCAN_INTERVAL = 15s), 6 scans = ~90s
                // This gives enough time for nodes to stabilize but not too long
                uint32_t fastScanInterval = 15; // 0.5 * SCAN_INTERVAL in seconds
                uint32_t expectedDelay = EMPTY_SCAN_THRESHOLD * fastScanInterval;
                
                REQUIRE(expectedDelay == 90); // ~1.5 minutes
                REQUIRE(expectedDelay < 120); // Less than 2 minutes
            }
        }
    }
}

SCENARIO("Channel re-detection behavior") {
    GIVEN("Documentation of expected channel re-scan behavior") {
        WHEN("A node cannot find mesh nodes on current channel") {
            THEN("After threshold is reached, full channel scan is triggered") {
                // This test documents the expected flow:
                // 1. Node scans on current channel (e.g., channel 1)
                // 2. Finds no mesh nodes, increments consecutiveEmptyScans
                // 3. After EMPTY_SCAN_THRESHOLD scans, triggers scanForMeshChannel()
                // 4. scanForMeshChannel() scans ALL channels (1-13)
                // 5. If mesh found on different channel, updates mesh->_meshChannel
                // 6. Restarts AP on new channel to match mesh
                
                REQUIRE(true); // This is a documentation test
            }
        }
        
        WHEN("Mesh is found on a different channel") {
            THEN("Node updates its channel and restarts AP") {
                // Expected behavior:
                // - Old channel: 1 (default)
                // - Detected channel: 6 (router's channel)
                // - Actions:
                //   1. mesh->_meshChannel = 6
                //   2. channel = 6
                //   3. WiFi.softAPdisconnect(false)
                //   4. wifiMesh->apInit(nodeId) with new channel
                
                REQUIRE(true); // This is a documentation test
            }
        }
        
        WHEN("Bridge promotes and switches channels") {
            THEN("Takeover announcement is sent on both channels") {
                // Expected behavior:
                // 1. Node wins election on channel 1
                // 2. Sends takeover announcement on channel 1 (current channel)
                // 3. Calls stop() and initAsBridge()
                // 4. Connects to router, detects channel 6
                // 5. Initializes mesh on channel 6
                // 6. Sends follow-up takeover announcement on channel 6
                //
                // This ensures:
                // - Nodes still on channel 1 hear the first announcement
                // - Nodes that switch to channel 6 hear the second announcement
                
                REQUIRE(true); // This is a documentation test
            }
        }
    }
}

SCENARIO("Channel re-detection prevents false triggers") {
    GIVEN("The consecutiveEmptyScans counter") {
        WHEN("Mesh nodes are found") {
            THEN("Counter is reset to zero") {
                // This prevents false triggers when:
                // - Network is temporarily unstable
                // - Node briefly loses connectivity
                // - Scanning happens during mesh reconfiguration
                
                REQUIRE(true); // This is a documentation test
            }
        }
        
        WHEN("Node is already connected to a mesh node") {
            THEN("Re-scan is only triggered if WiFi.status() != WL_CONNECTED") {
                // This prevents unnecessary channel scans when:
                // - Node is stably connected via STA
                // - No unknown nodes visible (all known nodes already connected)
                // - Network is healthy and stable
                
                REQUIRE(true); // This is a documentation test
            }
        }
    }
}

SCENARIO("Bridge election defers to channel re-sync when mesh connectivity is lost") {
    GIVEN("A node with lost mesh connectivity") {
        WHEN("Bridge election is triggered but empty scans indicate channel mismatch") {
            THEN("Election is deferred to allow channel re-sync to complete") {
                // This test documents the fix for issue #137:
                // 
                // Problem:
                // - Bridge switches channels (e.g., channel 1 -> 4 to match router)
                // - Other nodes lose mesh connectivity
                // - Bridge monitor triggers election after 30 seconds
                // - Nodes try to become bridge instead of re-syncing channel
                //
                // Solution:
                // - startBridgeElection() checks consecutiveEmptyScans counter
                // - If >= 3 empty scans and not connected, defer election
                // - This allows channel re-sync logic to run first (threshold = 6)
                // - Node will find mesh on new channel before trying to become bridge
                //
                // Expected behavior:
                // 1. Node loses mesh connectivity (bridge switched channels)
                // 2. Empty scans: 1, 2, 3... (fast scanning every 15 seconds)
                // 3. At scan 3: Bridge monitor triggers election
                // 4. startBridgeElection() detects emptyScans >= 3
                // 5. Election is deferred: "deferring election to allow channel re-sync"
                // 6. At scan 6: Channel re-sync triggers, finds mesh on new channel
                // 7. Node updates to new channel and reconnects
                // 8. Mesh connectivity restored without unnecessary bridge election
                
                REQUIRE(true); // This is a documentation test
            }
        }
        
        WHEN("Node has router credentials but mesh is on different channel") {
            THEN("Channel re-sync is prioritized over becoming a bridge") {
                // Benefits:
                // - Maintains mesh topology (fewer bridges = more stable)
                // - Avoids unnecessary router connections
                // - Reduces network churn and reconnection overhead
                // - Ensures nodes follow the primary bridge's channel
                
                REQUIRE(true); // This is a documentation test
            }
        }
    }
}
