// ====================================================================
// FILE: composables/useDatasetChangeDetection.ts
// ====================================================================

import { computed, Ref } from 'vue';
import type { Dataset } from '@/Dataset';
import { InertiaForm } from '@inertiajs/vue3';

interface ComparisonOptions {
    orderSensitive?: boolean;
    compareKey?: string;
}

export function useDatasetChangeDetection(
    form: InertiaForm<Dataset>,
    originalDataset: Ref<Dataset>
) {
    /**
     * Compare arrays with order sensitivity
     */
    const compareArraysWithOrder = (
        current: any[],
        original: any[],
        compareKey?: string
    ): boolean => {
        if (current.length !== original.length) return true;

        for (let i = 0; i < current.length; i++) {
            const currentItem = current[i];
            const originalItem = original[i];

            if (compareKey && currentItem[compareKey] !== originalItem[compareKey]) {
                return true;
            }

            if (JSON.stringify(currentItem) !== JSON.stringify(originalItem)) {
                return true;
            }
        }

        return false;
    };

    /**
     * Compare arrays without order sensitivity (content-based)
     */
    const compareArraysContent = (current: any[], original: any[]): boolean => {
        if (current.length !== original.length) return true;

        const normalizedCurrent = current
            .map((item) => JSON.stringify(item))
            .sort();
        const normalizedOriginal = original
            .map((item) => JSON.stringify(item))
            .sort();

        return (
            JSON.stringify(normalizedCurrent) !== JSON.stringify(normalizedOriginal)
        );
    };

    /**
     * Check if licenses have changed
     */
    const hasLicenseChanges = (): boolean => {
        const originalLicenses = Array.isArray(originalDataset.value.licenses)
            ? originalDataset.value.licenses
                .map((l) => (typeof l === 'object' ? l.id.toString() : String(l)))
                .sort()
            : [];

        const currentLicenses = Array.isArray(form.licenses)
            ? form.licenses
                .map((l) => (typeof l === 'object' ? l.id.toString() : String(l)))
                .sort()
            : [];

        return JSON.stringify(currentLicenses) !== JSON.stringify(originalLicenses);
    };

    /**
     * Check if basic properties have changed
     */
    const hasBasicPropertyChanges = (): boolean => {
        const original = originalDataset.value;

        return (
            form.language !== original.language ||
            form.type !== original.type ||
            form.creating_corporation !== original.creating_corporation ||
            Number(form.project_id) !== Number(original.project_id) ||
            form.embargo_date !== original.embargo_date
        );
    };

    /**
     * Check if there are items marked for deletion
     */
    const hasDeletionChanges = (): boolean => {
        return (
            (form.subjectsToDelete?.length ?? 0) > 0 ||
            (form.referencesToDelete?.length ?? 0) > 0
        );
    };

    /**
     * Check if files have changed
     */
    const hasFileChanges = (): boolean => {
        const currentFiles = form.files || [];
        const originalFiles = originalDataset.value.files || [];

        // Check for new files
        const newFiles = currentFiles.filter((f) => !f.id);
        if (newFiles.length > 0) return true;

        // Check for deleted files
        const originalFileIds = originalFiles.map((f) => f.id).filter(Boolean);
        const currentFileIds = currentFiles.map((f) => f.id).filter(Boolean);
        if (!originalFileIds.every((id) => currentFileIds.includes(id))) {
            return true;
        }

        // Check for file order changes
        return compareArraysWithOrder(currentFiles, originalFiles, 'sort_order');
    };

    /**
     * Check if coverage has changed
     */
    const hasCoverageChanges = (): boolean => {
        const currentCoverage = form.coverage || {};
        const originalCoverage = originalDataset.value.coverage || {};

        return (
            Number(currentCoverage.x_min) !== Number(originalCoverage.x_min) ||
            Number(currentCoverage.x_max) !== Number(originalCoverage.x_max) ||
            Number(currentCoverage.y_min) !== Number(originalCoverage.y_min) ||
            Number(currentCoverage.y_max) !== Number(originalCoverage.y_max)
        );
    };

    /**
     * Main change detection computed property
     */
    const hasUnsavedChanges = computed(() => {
          // Check if form is processing
        if (form.processing) return true;

        const original = originalDataset.value;

        // Check basic properties
        if (hasBasicPropertyChanges()) return true;

        // Check deletion arrays
        if (hasDeletionChanges()) return true;

        // Check licenses
        if (hasLicenseChanges()) return true;

        // Check files (order-sensitive)
        if (hasFileChanges()) return true;

        // Check authors (order-sensitive)
        if (
            compareArraysWithOrder(
                form.authors || [],
                original.authors || []
            )
        ) {
            return true;
        }

        // Check contributors (order-sensitive)
        if (
            compareArraysWithOrder(
                form.contributors || [],
                original.contributors || []
            )
        ) {
            return true;
        }

        // Check titles (order-sensitive)
        if (compareArraysWithOrder(form.titles, original.titles)) {
            return true;
        }

        // Check descriptions (order-sensitive)
        if (compareArraysWithOrder(form.descriptions, original.descriptions)) {
            return true;
        }

        // Check subjects/keywords (order-insensitive)
        if (
            compareArraysContent(
                form.subjects || [],
                original.subjects || []
            )
        ) {
            return true;
        }

        // Check references (order-insensitive)
        if (
            compareArraysContent(
                form.references || [],
                original.references || []
            )
        ) {
            return true;
        }

        // Check coverage
        if (hasCoverageChanges()) return true;

        return false;
    });

    /**
     * Analyze array changes with detailed information
     */
    const analyzeArrayChanges = (
        current: any[],
        original: any[],
        itemName: string
    ): string[] => {
        const changes: string[] = [];

        // Check for count changes
        if (current.length !== original.length) {
            const diff = current.length - original.length;
            if (diff > 0) {
                changes.push(`${diff} ${itemName}(s) added`);
            } else {
                changes.push(`${Math.abs(diff)} ${itemName}(s) removed`);
            }
        }

        // Check for order changes (only if same count)
        if (current.length === original.length && current.length > 1) {
            const currentIds = current.map((item) => item.id).filter(Boolean);
            const originalIds = original.map((item) => item.id).filter(Boolean);

            if (currentIds.length === originalIds.length && currentIds.length > 0) {
                const orderChanged = currentIds.some(
                    (id, index) => id !== originalIds[index]
                );
                if (orderChanged) {
                    changes.push(`${itemName} order changed`);
                }
            }
        }

        // Check for content changes
        if (current.length === original.length) {
            const contentChanged =
                JSON.stringify(current) !== JSON.stringify(original);
            const orderChanged = changes.some((change) =>
                change.includes('order changed')
            );

            if (contentChanged && !orderChanged) {
                changes.push(`${itemName} content modified`);
            }
        }

        return changes;
    };

    /**
     * Generate detailed changes summary
     */
    const getChangesSummary = (): string[] => {
        const changes: string[] = [];
        const original = originalDataset.value;

        // Basic property changes
        if (form.language !== original.language) {
            changes.push('Language changed');
        }
        if (form.type !== original.type) {
            changes.push('Dataset type changed');
        }
        if (form.creating_corporation !== original.creating_corporation) {
            changes.push('Creating corporation changed');
        }
        if (Number(form.project_id) !== Number(original.project_id)) {
            changes.push('Project changed');
        }
        if (form.embargo_date !== original.embargo_date) {
            changes.push('Embargo date changed');
        }

        // Deletion tracking
        if ((form.subjectsToDelete?.length ?? 0) > 0) {
            changes.push(
                `${form.subjectsToDelete.length} keyword(s) marked for deletion`
            );
        }
        if ((form.referencesToDelete?.length ?? 0) > 0) {
            changes.push(
                `${form.referencesToDelete.length} reference(s) marked for deletion`
            );
        }

        // License changes
        if (hasLicenseChanges()) {
            changes.push('Licenses modified');
        }

        // Files analysis
        const currentFiles = form.files || [];
        const originalFiles = original.files || [];
        const newFiles = currentFiles.filter((f) => !f.id);

        if (newFiles.length > 0) {
            changes.push(`${newFiles.length} new file(s) added`);
        }

        const existingCurrentFiles = currentFiles.filter((f) => f.id);
        const existingOriginalFiles = originalFiles.filter((f) => f.id);

        if (
            existingCurrentFiles.length === existingOriginalFiles.length &&
            existingCurrentFiles.length > 1
        ) {
            const currentOrder = existingCurrentFiles.map((f) => f.id);
            const originalOrder = existingOriginalFiles.map((f) => f.id);
            const orderChanged = currentOrder.some(
                (id, index) => id !== originalOrder[index]
            );

            if (orderChanged) {
                changes.push('File order changed');
            }
        }

        // Authors and contributors
        changes.push(
            ...analyzeArrayChanges(
                form.authors || [],
                original.authors || [],
                'author'
            )
        );
        changes.push(
            ...analyzeArrayChanges(
                form.contributors || [],
                original.contributors || [],
                'contributor'
            )
        );

        // Titles analysis
        if (JSON.stringify(form.titles) !== JSON.stringify(original.titles)) {
            if (form.titles.length !== original.titles.length) {
                const diff = form.titles.length - original.titles.length;
                changes.push(
                    diff > 0
                        ? `${diff} title(s) added`
                        : `${Math.abs(diff)} title(s) removed`
                );
            } else if (form.titles.length > 0) {
                if (form.titles[0]?.value !== original.titles[0]?.value) {
                    changes.push('Main title changed');
                }
                const otherTitlesChanged = form.titles
                    .slice(1)
                    .some(
                        (title, index) =>
                            JSON.stringify(title) !== JSON.stringify(original.titles[index + 1])
                    );
                if (otherTitlesChanged) {
                    changes.push('Additional titles modified');
                }
            }
        }

        // Descriptions analysis
        if (
            JSON.stringify(form.descriptions) !==
            JSON.stringify(original.descriptions)
        ) {
            if (form.descriptions.length !== original.descriptions.length) {
                const diff = form.descriptions.length - original.descriptions.length;
                changes.push(
                    diff > 0
                        ? `${diff} description(s) added`
                        : `${Math.abs(diff)} description(s) removed`
                );
            } else if (form.descriptions.length > 0) {
                if (
                    form.descriptions[0]?.value !== original.descriptions[0]?.value
                ) {
                    changes.push('Main abstract changed');
                }
                const otherDescChanged = form.descriptions
                    .slice(1)
                    .some(
                        (desc, index) =>
                            JSON.stringify(desc) !==
                            JSON.stringify(original.descriptions[index + 1])
                    );
                if (otherDescChanged) {
                    changes.push('Additional descriptions modified');
                }
            }
        }

        // Subjects/Keywords analysis
        const currentSubjects = form.subjects || [];
        const originalSubjects = original.subjects || [];
        if (currentSubjects.length !== originalSubjects.length) {
            const diff = currentSubjects.length - originalSubjects.length;
            changes.push(
                diff > 0
                    ? `${diff} keyword(s) added`
                    : `${Math.abs(diff)} keyword(s) removed`
            );
        } else if (currentSubjects.length > 0) {
            const currentSubjectsNormalized = currentSubjects
                .map((s) => JSON.stringify(s))
                .sort();
            const originalSubjectsNormalized = originalSubjects
                .map((s) => JSON.stringify(s))
                .sort();
            if (
                JSON.stringify(currentSubjectsNormalized) !==
                JSON.stringify(originalSubjectsNormalized)
            ) {
                changes.push('Keywords modified');
            }
        }

        // References analysis
        const currentRefs = form.references || [];
        const originalRefs = original.references || [];
        if (currentRefs.length !== originalRefs.length) {
            const diff = currentRefs.length - originalRefs.length;
            changes.push(
                diff > 0
                    ? `${diff} reference(s) added`
                    : `${Math.abs(diff)} reference(s) removed`
            );
        } else if (currentRefs.length > 0) {
            const currentRefsNormalized = currentRefs
                .map((r) => JSON.stringify(r))
                .sort();
            const originalRefsNormalized = originalRefs
                .map((r) => JSON.stringify(r))
                .sort();
            if (
                JSON.stringify(currentRefsNormalized) !==
                JSON.stringify(originalRefsNormalized)
            ) {
                changes.push('References modified');
            }
        }

        // Coverage changes
        if (hasCoverageChanges()) {
            changes.push('Geographic coverage changed');
        }

        return changes;
    };

    return {
        hasUnsavedChanges,
        getChangesSummary,
        compareArraysWithOrder,
        compareArraysContent,
    };
}