// State
let rawGeoJSON = null;
let cleanedGeoJSON = null;
let analysisLog = [];
let overlapCsvData = [];
let originalFileName = "polygons";

// DOM Elements
const dropZone = document.getElementById('dropZone');
const fileInput = document.getElementById('geojsonFile');
const fileLabelText = document.getElementById('fileLabelText');
const analyzeBtn = document.getElementById('analyzeBtn');
const resultsCard = document.getElementById('resultsCard');
const logOutput = document.getElementById('logOutput');
const downloadLogBtn = document.getElementById('downloadLogBtn');
const downloadCsvBtn = document.getElementById('downloadCsvBtn');
const editCard = document.getElementById('editCard');
const applyEditsBtn = document.getElementById('applyEditsBtn');
const editResults = document.getElementById('editResults');
const editLogOutput = document.getElementById('editLogOutput');
const downloadCleanedBtn = document.getElementById('downloadCleanedBtn');
const downloadEditLogBtn = document.getElementById('downloadEditLogBtn');

// Event Listeners
dropZone.addEventListener('dragover', (e) => {
    e.preventDefault();
    dropZone.style.backgroundColor = '#e0f2f1';
});
dropZone.addEventListener('dragleave', (e) => {
    e.preventDefault();
    dropZone.style.backgroundColor = 'rgba(42, 171, 149, 0.05)';
});
dropZone.addEventListener('drop', (e) => {
    e.preventDefault();
    dropZone.style.backgroundColor = 'rgba(42, 171, 149, 0.05)';
    if (e.dataTransfer.files.length) {
        fileInput.files = e.dataTransfer.files;
        handleFile(e.dataTransfer.files[0]);
    }
});
fileInput.addEventListener('change', (e) => {
    if (fileInput.files.length) {
        handleFile(fileInput.files[0]);
    }
});

analyzeBtn.addEventListener('click', runAnalysis);
downloadLogBtn.addEventListener('click', () => downloadText(analysisLog.join('\n'), `${originalFileName}_log.txt`));
downloadCsvBtn.addEventListener('click', downloadCsv);
applyEditsBtn.addEventListener('click', runEdits);
downloadCleanedBtn.addEventListener('click', () => downloadJson(cleanedGeoJSON, `${originalFileName}_SmartCane.geojson`));

// Logic

function handleFile(file) {
    originalFileName = file.name.replace(/\.geojson$/i, '').replace(/\.json$/i, '');
    fileLabelText.innerHTML = `<strong>${file.name}</strong><br><small>Ready to analyze</small>`;
    
    const reader = new FileReader();
    reader.onload = (e) => {
        try {
            rawGeoJSON = JSON.parse(e.target.result);
            analyzeBtn.disabled = false;
            // Reset UI
            resultsCard.classList.add('hidden');
            editCard.classList.add('hidden');
            editResults.classList.add('hidden');
        } catch (err) {
            alert("Invalid GeoJSON file");
            console.error(err);
        }
    };
    reader.readAsText(file);
}

function log(msg, targetLog = analysisLog, targetEl = logOutput) {
    // Add timestamp or just raw msg? R script uses simple text.
    targetLog.push(msg);
    targetEl.innerText = targetLog.join('\n');
    // Auto scroll
    targetEl.scrollTop = targetEl.scrollHeight;
}

async function runAnalysis() {
    // Reset
    analysisLog = [];
    overlapCsvData = [];
    resultsCard.classList.remove('hidden');
    editCard.classList.add('hidden');
    analyzeBtn.disabled = true;
    analyzeBtn.innerText = "Analyzing...";

    // Use setTimeout to allow UI to update
    setTimeout(async () => {
        try {
            await analyze();
            analyzeBtn.disabled = false;
            analyzeBtn.innerText = "Analyze Polygons";
            editCard.classList.remove('hidden');
        } catch (err) {
            console.error(err);
            log(`ERROR: ${err.message}`);
            analyzeBtn.disabled = false;
            analyzeBtn.innerText = "Analyze Polygons";
        }
    }, 100);
}

function cleanDuplicateVertices(feature) {
    if (feature.geometry.type === 'Polygon') {
        feature.geometry.coordinates = feature.geometry.coordinates.map(ring => 
            ring.filter((coord, i, arr) => 
                i === 0 || JSON.stringify(coord) !== JSON.stringify(arr[i - 1])
            )
        );
    } else if (feature.geometry.type === 'MultiPolygon') {
        feature.geometry.coordinates = feature.geometry.coordinates.map(polygon =>
            polygon.map(ring =>
                ring.filter((coord, i, arr) => 
                    i === 0 || JSON.stringify(coord) !== JSON.stringify(arr[i - 1])
                )
            )
        );
    }
    return feature;
}

async function analyze() {
    log(`Processing log for: ${originalFileName}`);
    log("==================================================");
    
    let features = rawGeoJSON.features;
    if (!features) {
        log("Error: No features found in GeoJSON.");
        return;
    }

    log(`${features.length} geometries found.`);

    // 1. Check duplicates FIRST
    log("\n=== Checking for duplicates... ===");
    const fieldCounts = {};
    features.forEach(f => {
        const id = getFieldNo(f);
        if (id) {
            fieldCounts[id] = (fieldCounts[id] || 0) + 1;
        }
    });

    const duplicates = Object.entries(fieldCounts).filter(([id, count]) => count > 1);
    
    if (duplicates.length > 0) {
        log(`✕ ${duplicates.length} duplicate field codes detected.`);
        log("Removing duplicate fields...");
        
        const duplicateIds = new Set(duplicates.map(d => d[0]));
        const beforeDedup = features.length;
        features = features.filter(f => !duplicateIds.has(getFieldNo(f)));
        
        duplicates.forEach(d => {
             log(`• Field ${d[0]}: ${d[1]} occurrences (Removed)`);
        });
        
        log(`✓ Removed ${beforeDedup - features.length} duplicate entries!`);
    } else {
        log("✓ No duplicates found!");
    }

    // 2. Filter empty
    log("\n=== Checking empty geometries... ===");
    const initialCount = features.length;
    features = features.filter(f => f.geometry && f.geometry.coordinates && f.geometry.coordinates.length > 0);
    const emptyCount = initialCount - features.length;
    
    if (emptyCount > 0) {
        log(`${emptyCount} empty geometries detected! Deleting...`);
    } else {
        log(`✓ No empty geometries found.`);
    }

    // 3. Clean duplicate vertices & validity check
    log("\n=== Cleaning duplicate vertices & checking geometry validity... ===");
    let invalidCount = 0;
    let duplicateVertexCount = 0;
    
    let fixedFeatures = [];
    for (let f of features) {
        // Clean duplicate vertices first
        const beforeClean = JSON.stringify(f.geometry);
        f = cleanDuplicateVertices(f);
        const afterClean = JSON.stringify(f.geometry);
        
        if (beforeClean !== afterClean) {
            duplicateVertexCount++;
        }
        
        // Drop Z if present (Turf truncate)
        f = turf.truncate(f, {precision: 6, coordinates: 2});
        
        try {
            const kinks = turf.kinks(f);
            if (kinks.features.length > 0) {
                invalidCount++;
                // Try to fix by unkinking
                const unkinked = turf.unkinkPolygon(f);
                unkinked.features.forEach(uf => {
                    uf.properties = {...f.properties};
                    fixedFeatures.push(uf);
                });
            } else {
                fixedFeatures.push(f);
            }
        } catch (e) {
            log(`⚠ Warning: Could not process geometry for ${getFieldNo(f)}: ${e.message}`);
            // Still add it, but log the issue
            fixedFeatures.push(f);
        }
    }
    
    if (duplicateVertexCount > 0) {
        log(`✓ Cleaned duplicate vertices in ${duplicateVertexCount} geometries.`);
    }
    
    if (invalidCount > 0) {
        log(`✕ ${invalidCount} invalid geometries detected (self-intersections). Attempting fix...`);
        log(`✓ Fixed by splitting self-intersections.`);
    } else {
        log(`✓ All geometries valid (no self-intersections).`);
    }
    features = fixedFeatures;
    log(`Current geometry count: ${features.length}`);

    // 4. Check Overlaps
    log("\n=== Checking for plot overlap... ===");
    
    // Build RBush Index
    const tree = new RBush();
    const items = features.map((f, index) => {
        const bbox = turf.bbox(f);
        return {
            minX: bbox[0],
            minY: bbox[1],
            maxX: bbox[2],
            maxY: bbox[3],
            feature: f,
            id: getFieldNo(f) || `Unknown-${index}`,
            area: turf.area(f),
            index: index
        };
    });
    tree.load(items);

    const overlaps = [];
    const checkedPairs = new Set();
    let fieldsWithOverlap = new Set();

    for (let i = 0; i < items.length; i++) {
        const itemA = items[i];
        const candidates = tree.search(itemA);
        
        for (const itemB of candidates) {
            if (itemA.index === itemB.index) continue;
            
            // Sort IDs to ensure uniqueness of pair
            const pairId = [itemA.index, itemB.index].sort().join('_');
            if (checkedPairs.has(pairId)) continue;
            checkedPairs.add(pairId);
            
            // Check intersection
            let intersection = null;
            try {
                intersection = turf.intersect(itemA.feature, itemB.feature);
            } catch (e) {
                console.warn("Intersection error", e);
            }

            if (intersection) {
                const intersectArea = turf.area(intersection);
                if (intersectArea > 1) {                                  
                    overlaps.push({
                        a: itemA,
                        b: itemB,
                        area: intersectArea
                    });
                    
                    fieldsWithOverlap.add(itemA.id);
                    fieldsWithOverlap.add(itemB.id);
                }
            }
        }
    }

    if (overlaps.length > 0) {
        log(`✕ ${fieldsWithOverlap.size} fields with overlap found.`);
        
        // We need to calculate total overlap percentage for each field to decide if it's > 30%
        // Map: FieldID -> TotalOverlapArea
        const fieldOverlapMap = {};
        
        overlaps.forEach(o => {
            // Add to A
            if (!fieldOverlapMap[o.a.id]) fieldOverlapMap[o.a.id] = 0;
            fieldOverlapMap[o.a.id] += o.area;
            
            // Add to B
            if (!fieldOverlapMap[o.b.id]) fieldOverlapMap[o.b.id] = 0;
            fieldOverlapMap[o.b.id] += o.area;
        });
        
        // Report significant overlaps
        let severeCount = 0;
        
        Object.keys(fieldOverlapMap).forEach(fid => {
            const item = items.find(it => it.id === fid); // This lookup might be slow if many items, but okay for now
            if (!item) return;
            
            const totalOverlap = fieldOverlapMap[fid];
            const originalArea = item.area;
            const pct = (totalOverlap / originalArea) * 100;
            
            let category = "<30%";
            if (pct >= 30) category = ">30%";
            
            // Add to CSV Data
            overlapCsvData.push({
                Field_No: fid,
                Original_Area_ha: (originalArea / 10000).toFixed(4),
                Overlap_Area_ha: (totalOverlap / 10000).toFixed(4),
                Overlap_Percentage: pct.toFixed(1),
                Overlap_Category: category
            });

            if (pct > 30) {
                log(`Field number ${fid} overlap >30% (${pct.toFixed(1)}%) -- Will be deleted`);
                severeCount++;
            }
        });
        
        if (severeCount === 0) {
             log("✓ No significant overlap (>30%) detected.");
        } else {
             log(`✕ ${severeCount} fields have significant overlap (>30%).`);
        }
        
    } else {
        log("✓ No overlap found!");
    }

    // Save state for editing
    // We keep 'features' (which are fixed/deduplicated)
    rawGeoJSON.features = features; 

}

function getFieldNo(feature) {
    return feature.properties['Field No'] || feature.properties['field'] || feature.properties['Field_No'];
}

async function runEdits() {
    const editLog = [];
    editResults.classList.remove('hidden');
    editLogOutput.innerText = "Processing edits...";
    
    function logEdit(msg) {
        editLog.push(msg);
        editLogOutput.innerText = editLog.join('\n');
         editLogOutput.scrollTop = editLogOutput.scrollHeight;
    }

    setTimeout(async () => {
        let features = rawGeoJSON.features;
        
        // Clean all features before processing
        features = features.map(f => cleanDuplicateVertices(f));
        
        let delCount = 0;

        // 1. Remove > 30% overlaps
        // We need to re-calculate overlaps because we want to be precise
        
        // Build Index again
        let tree = new RBush();
        let items = features.map((f, index) => ({
            minX: turf.bbox(f)[0],
            minY: turf.bbox(f)[1],
            maxX: turf.bbox(f)[2],
            maxY: turf.bbox(f)[3],
            feature: f,
            id: getFieldNo(f),
            area: turf.area(f),
            index: index
        }));
        tree.load(items);

        // Calculate overlap per field
        let fieldOverlapMap = {};
        
        // Find all overlaps
        // Note: This is slightly inefficient to re-do, but safer.
        for (let i = 0; i < items.length; i++) {
            const itemA = items[i];
            const candidates = tree.search(itemA);
            for (const itemB of candidates) {
                if (itemA.index < itemB.index) { // Only check pair once
                    const intersection = turf.intersect(itemA.feature, itemB.feature);
                    if (intersection) {
                        const area = turf.area(intersection);
                        if (area > 1) {
                            if (!fieldOverlapMap[itemA.id]) fieldOverlapMap[itemA.id] = 0;
                            fieldOverlapMap[itemA.id] += area;
                            
                            if (!fieldOverlapMap[itemB.id]) fieldOverlapMap[itemB.id] = 0;
                            fieldOverlapMap[itemB.id] += area;
                        }
                    }
                }
            }
        }

        // Identify fields to delete
        const toDelete = new Set();
        Object.keys(fieldOverlapMap).forEach(fid => {
            const item = items.find(it => it.id == fid);
            if (item) {
                const pct = (fieldOverlapMap[fid] / item.area) * 100;
                if (pct > 30) {
                    toDelete.add(fid);
                    logEdit(`Field ${fid} overlap ${pct.toFixed(1)}% > 30% -- ✕ Deleted!`);
                    delCount++;
                }
            }
        });

        // Apply Deletion
        features = features.filter(f => !toDelete.has(getFieldNo(f)));
        
        if (delCount > 0) {
            logEdit(`✓ Significant overlap fixed - ${delCount} geometries deleted.`);
        } else {
             logEdit(`✓ No significant overlap detected.`);
        }

        // 2. Fix remaining overlaps (< 30%)
        // Loop through intersections and split up difference
        logEdit("\nChecking for remaining overlaps (<30%) to fix...");
        
        // Re-index with remaining features
        items = features.map((f, index) => ({
            minX: turf.bbox(f)[0],
            minY: turf.bbox(f)[1],
            maxX: turf.bbox(f)[2],
            maxY: turf.bbox(f)[3],
            feature: f,
            id: getFieldNo(f),
            area: turf.area(f),
            index: index
        }));
        tree = new RBush();
        tree.load(items);
        
        let fixCount = 0;
        
        let pairs = [];
        for (let i = 0; i < items.length; i++) {
            const itemA = items[i];
            const candidates = tree.search(itemA);
            for (const itemB of candidates) {
                if (itemA.index < itemB.index) {
                     const intersection = turf.intersect(itemA.feature, itemB.feature);
                     if (intersection && turf.area(intersection) > 1) {
                         pairs.push({a: itemA, b: itemB});
                     }
                }
            }
        }
               
        for (const pair of pairs) {
            const f1 = pair.a.feature; // Reference to object in 'features' array
            const f2 = pair.b.feature;
            
            // Check if they are still valid/exist (in case we deleted one? No we filtered already)
            // Re-check intersection because one might have been modified by a previous iteration
            const intersection = turf.intersect(f1, f2);
            if (!intersection || turf.area(intersection) <= 1) continue;
            
            const area1 = turf.area(f1);
            const area2 = turf.area(f2);
            
            // "Add the overlapping area to the biggest plot"
            // Means subtract overlap from the smallest plot.
            
            let updated = false;
            if (area1 > area2) {
                // f1 is bigger. Subtract f1 from f2.
                // poly2 <- st_difference(poly2, st_union(poly1))
                // effectively poly2 = poly2 - poly1
                try {
                    const diff = turf.difference(f2, f1);
                    if (diff) {
                        f2.geometry = diff.geometry;
                        updated = true;
                        logEdit(`✓ Fixed conflict between ${getFieldNo(f1)} and ${getFieldNo(f2)} (Trimmed ${getFieldNo(f2)})`);
                    } else {
                         // f2 completely inside f1?
                         logEdit(`! ${getFieldNo(f2)} is completely inside ${getFieldNo(f1)} - Removed ${getFieldNo(f2)}`);
                         features = features.filter(f => f !== f2);
                    }
                } catch(e) {
                    console.warn("Difference failed", e);
                }
            } else {
                // f2 is bigger or equal. Subtract f2 from f1.
                try {
                     const diff = turf.difference(f1, f2);
                     if (diff) {
                         f1.geometry = diff.geometry;
                         updated = true;
                         logEdit(`✓ Fixed conflict between ${getFieldNo(f1)} and ${getFieldNo(f2)} (Trimmed ${getFieldNo(f1)})`);
                     } else {
                         logEdit(`! ${getFieldNo(f1)} is completely inside ${getFieldNo(f2)} - Removed ${getFieldNo(f1)}`);
                         features = features.filter(f => f !== f1);
                     }
                } catch(e) {
                     console.warn("Difference failed", e);
                }
            }
            
            if (updated) fixCount++;
        }
        
        if (fixCount === 0) {
            logEdit("✓ No <30% overlap detected.");
        }

        // 3. Dissolve/Merge polygons by field ID
        logEdit("\n=== Dissolving polygons by field ID... ===");
        
        // Group features by field ID
        const groupedByField = {};
        features.forEach(f => {
            const fieldId = getFieldNo(f);
            if (!groupedByField[fieldId]) {
                groupedByField[fieldId] = [];
            }
            groupedByField[fieldId].push(f);
        });
        
        let dissolveCount = 0;
        const dissolvedFeatures = [];
        
        Object.keys(groupedByField).forEach(fieldId => {
            const group = groupedByField[fieldId];
            
            if (group.length === 1) {
                // No dissolve needed
                dissolvedFeatures.push(group[0]);
            } else {
                // Multiple polygons with same field ID - need to union them
                logEdit(`  Dissolving ${group.length} polygons for field ${fieldId}...`);
                
                try {
                    // Union all geometries for this field
                    let unionGeom = group[0];
                    
                    for (let i = 1; i < group.length; i++) {
                        unionGeom = turf.union(unionGeom, group[i]);
                        if (!unionGeom) {
                            logEdit(`⚠ Warning: Could not union all parts of field ${fieldId}`);
                            // Fall back to keeping individual parts
                            dissolvedFeatures.push(...group);
                            return;
                        }
                    }
                    
                    // Preserve original properties from first feature
                    unionGeom.properties = {...group[0].properties};
                    dissolvedFeatures.push(unionGeom);
                    dissolveCount++;
                    logEdit(`✓ Field ${fieldId}: Merged ${group.length} parts into 1`);
                } catch (e) {
                    logEdit(`⚠ Error dissolving field ${fieldId}: ${e.message}`);
                    // Fall back to keeping individual parts
                    dissolvedFeatures.push(...group);
                }
            }
        });
        
        if (dissolveCount > 0) {
            logEdit(`✓ Dissolved ${dissolveCount} fields with multiple parts.`);
        } else {
            logEdit(`✓ No multi-part fields detected.`);
        }
        
        features = dissolvedFeatures;
        
        // Prepare download
        cleanedGeoJSON = {
            type: "FeatureCollection",
            features: features,
            crs: rawGeoJSON.crs
        };
        
        logEdit("\n=== Saving edited shapefiles... ===");
        logEdit(`✓ Ready to download ${features.length} geometries.`);

        // Add event listener for download edit log
        downloadEditLogBtn.onclick = () => downloadText(editLog.join('\n'), `${originalFileName}_edit_log.txt`);

    }, 100);
}

function downloadText(content, filename) {
    const blob = new Blob([content], {type: "text/plain;charset=utf-8"});
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = filename;
    a.click();
    URL.revokeObjectURL(url);
}

function downloadJson(content, filename) {
    const blob = new Blob([JSON.stringify(content, null, 2)], {type: "application/json"});
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = filename;
    a.click();
    URL.revokeObjectURL(url);
}

function downloadCsv() {
    if (overlapCsvData.length === 0) {
        alert("No overlap data to download.");
        return;
    }
    const headers = Object.keys(overlapCsvData[0]);
    const rows = overlapCsvData.map(row => headers.map(h => row[h]).join(','));
    const csvContent = [headers.join(',')].concat(rows).join('\n');
    downloadText(csvContent, `${originalFileName}_overlap_details.csv`);
}