// *****************************************************************************
// Copyright (C) 2026 EclipseSource GmbH and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// http://www.eclipse.org/legal/epl-2.0.
//
// This Source Code may also be made available under the following Secondary
// Licenses when the conditions for such availability set forth in the Eclipse
// Public License v. 2.0 are satisfied: GNU General Public License, version 2
// with the GNU Classpath Exception which is available at
// https://www.gnu.org/software/classpath/license.html.
//
// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
// *****************************************************************************

import { ScmHistoryItemRef, ScmHistoryItemChange } from './scm-provider';

/**
 * Returns the CSS color variable for the given lane index.
 * Uses Theia's `--theia-scmGraph-*` variables, mirroring the VS Code
 * scm graph color scheme:
 *   lane 0 (current ref)  → historyItemRefColor
 *   lane 1 (remote ref)   → historyItemRemoteRefColor
 *   lane 2 (base ref)     → historyItemBaseRefColor
 *   lane 3–7              → foreground1–5
 */
export function laneColor(index: number): string {
    switch (index % 8) {
        case 0: return 'var(--theia-scmGraph-historyItemRefColor)';
        case 1: return 'var(--theia-scmGraph-historyItemRemoteRefColor)';
        case 2: return 'var(--theia-scmGraph-historyItemBaseRefColor)';
        case 3: return 'var(--theia-scmGraph-foreground1)';
        case 4: return 'var(--theia-scmGraph-foreground2)';
        case 5: return 'var(--theia-scmGraph-foreground3)';
        case 6: return 'var(--theia-scmGraph-foreground4)';
        default: return 'var(--theia-scmGraph-foreground5)';
    }
}

export function getChangeStatus(change: ScmHistoryItemChange): string {
    if (!change.originalUri) {
        return 'A';
    }
    if (!change.modifiedUri) {
        return 'D';
    }
    if (change.renameUri) {
        return 'R';
    }
    return 'M';
}

export function getFileName(uri: string): string {
    const parts = uri.split('/');
    return parts[parts.length - 1] || uri;
}

export function getFilePath(uri: string): string {
    try {
        const u = new URL(uri);
        return u.pathname;
    } catch {
        return uri;
    }
}

/**
 * Returns the repo-relative path of the given URI, stripping the rootUri prefix.
 * Falls back to the full path if rootUri is unavailable or doesn't match.
 */
export function getRepoRelativePath(uri: string, rootUri: string | undefined): string {
    const fullPath = getFilePath(uri);
    if (!rootUri) {
        return fullPath;
    }
    const rootPath = getFilePath(rootUri);
    // Normalize: ensure rootPath ends with '/'
    const rootPrefix = rootPath.endsWith('/') ? rootPath : rootPath + '/';
    if (fullPath.startsWith(rootPrefix)) {
        return fullPath.slice(rootPrefix.length);
    }
    return fullPath;
}

export function getRefBadgeClass(ref: ScmHistoryItemRef): string {
    const cat = (ref.category ?? '').toLowerCase();
    if (cat === 'heads' || cat === 'head' || ref.id.startsWith('refs/heads/')) {
        return 'head';
    }
    if (cat === 'remotes' || cat === 'remote' || ref.id.startsWith('refs/remotes/')) {
        return 'remote';
    }
    if (cat === 'tags' || cat === 'tag' || ref.id.startsWith('refs/tags/')) {
        return 'tag';
    }
    if (cat === 'base') {
        return 'base';
    }
    return 'head';
}

export function isTagRef(ref: ScmHistoryItemRef): boolean {
    const cat = (ref.category ?? '').toLowerCase();
    if (cat === 'tags' || cat === 'tag') {
        return true;
    }
    // Fall back to checking the ref id prefix (e.g. 'refs/tags/v1.0')
    return ref.id.startsWith('refs/tags/');
}

export function isRemoteRef(ref: ScmHistoryItemRef): boolean {
    const cat = (ref.category ?? '').toLowerCase();
    if (cat === 'remotes' || cat === 'remote') {
        return true;
    }
    // Fall back to checking the ref id prefix (e.g. 'refs/remotes/origin/main')
    return ref.id.startsWith('refs/remotes/');
}

/**
 * Extracts the local branch name from a remote ref name like "origin/master" → "master".
 * Falls back to the full name if no slash is found.
 */
export function getLocalNameFromRemote(remoteName: string): string {
    const slashIdx = remoteName.indexOf('/');
    return slashIdx >= 0 ? remoteName.slice(slashIdx + 1) : remoteName;
}

export interface DeduplicatedRef {
    ref: ScmHistoryItemRef;
    /** True when both a local and a remote ref for this branch exist on this commit. */
    hasBoth: boolean;
}

/**
 * Deduplicates refs: when a local branch (e.g. "master") and a remote branch
 * (e.g. "origin/master") both appear, collapse them into one entry with `hasBoth=true`.
 * Tags and other ref types are passed through unchanged.
 */
export function deduplicateRefs(refs: readonly ScmHistoryItemRef[]): DeduplicatedRef[] {
    const localNames = new Set<string>();
    for (const ref of refs) {
        if (!isRemoteRef(ref) && !isTagRef(ref)) {
            localNames.add(ref.name.toLowerCase());
        }
    }

    const result: DeduplicatedRef[] = [];
    const suppressedRemotes = new Set<string>();

    // First pass: identify remote refs that have a matching local branch
    for (const ref of refs) {
        if (isRemoteRef(ref)) {
            const localName = getLocalNameFromRemote(ref.name).toLowerCase();
            if (localNames.has(localName)) {
                suppressedRemotes.add(ref.id);
            }
        }
    }

    // Second pass: emit all refs except suppressed remote ones;
    // mark local branches that have a matching remote with hasBoth=true
    for (const ref of refs) {
        if (suppressedRemotes.has(ref.id)) {
            continue;
        }
        const hasBoth = !isRemoteRef(ref) && !isTagRef(ref)
            ? refs.some(r => isRemoteRef(r) && getLocalNameFromRemote(r.name).toLowerCase() === ref.name.toLowerCase())
            : false;
        result.push({ ref, hasBoth });
    }

    return result;
}