/*
 * Git HTML Archive Viewer
 * 
 * Benedikt Bieringer <benedikt.b@wwu.de>
 * https://nuserv.uni-muenster.de:8443/bbieringer/statusarchiveviewer
 */

class ArchiveCommit {
    constructor(message, time, sha) {
        this.message = message
        this.time = time
        this.sha = sha
    }
}

function replace_urls(text, url_before, url_after) {
    for(const key of ["src=\""]) {
        segments = text.split(key)
        result_text = segments[0]
        for(const segment of segments.slice(1)) {
            var index = segment.indexOf('"')
            var first = segment.substring(0, index)
            var second = segment.substring(index)
            
            var new_url = url_before + encodeURIComponent(first) + url_after
            
            result_text += key + new_url + second
        }
        
        text = result_text
    }
    
    return text
}

function hide_iframes(text) {
    return text.replaceAll("<iframe", "<div hidden ").replaceAll("/iframe>", "/div>")
}

function date_to_iso(value) {
    if ((value + "").includes("-")) {
        return value
    }
    
    var date = new Date(parseInt(value)*1000)
    return date.toISOString().substring(0,16)
}

function date_to_unix(value) {
    return parseInt(new Date(value + ":00+00:00").getTime() / 1000)
}

class ArchiveView {
    constructor(mindate, maindiv, token, url, project_id, branch, page_path, index) {
       
        this.token = token
        this.url = url
        this.project_id = project_id
        this.branch = branch

        this.next_commit = ""
        this.current_commit = ""

        this.last_from = ""
        this.last_to = ""
        
        this.maindiv = maindiv
        
        var outer_span = document.createElement("span")
        this.maindiv.appendChild(outer_span)
        
        // ---
        
        this.selecttype = document.createElement("select")
        outer_span.appendChild(this.selecttype)
        
        var option_date = document.createElement("option")
        option_date.value = "date"
        option_date.innerHTML = "Date"
        this.selecttype.appendChild(option_date)
        
        var option_range = document.createElement("option")
        option_range.value = "range"
        option_range.innerHTML = "Range"
        this.selecttype.appendChild(option_range)
        
        this.selecttype.addEventListener("input",(() => this.update_hash()))
        
        // ---
        
        outer_span.append(" (" + mindate + " to today): ")
        
        this.dateselector = document.createElement("input")
        this.dateselector.type = "date"
        
        // Alternative, doesn't allow selecting today in first two hours of day:
        // var maxdate = new Date().toISOString().split("T")[0]
        var maxdate = new Date().toLocaleDateString('en-ca')
        this.dateselector.value = ""
        this.dateselector.max = maxdate
        this.dateselector.addEventListener("input",(() => this.update_hash()))
        
        outer_span.appendChild(this.dateselector)
        
        // ---
        
        this.rangespan = document.createElement("span")
        outer_span.appendChild(this.rangespan)
        
        
        this.range_from = document.createElement("input")
        this.range_from.type = "datetime-local"
        
        this.range_from.value = ""
        this.range_from.min = mindate + "T00:00"
        this.range_from.max = maxdate + "T23:59"
        this.range_from.addEventListener("input",(() => this.update_hash()))
        
        this.rangespan.appendChild(this.range_from)
        
        
        this.rangespan.insertAdjacentHTML('beforeend', " &ndash; ")
        
        
        this.range_to = document.createElement("input")
        this.range_to.type = "datetime-local"
        this.range_to.disabled = true
        
        this.range_to.value = ""
        this.range_to.max = maxdate + "T23:59"
        this.range_to.addEventListener("input",(() => this.update_hash()))

        this.rangespan.appendChild(this.range_to)
        
        // ---
        
        outer_span.append(" | Version: ")
        
        this.commitsSelect = document.createElement("select")
        this.commitsSelect.className = "archive commits"

        this.commitsSelect.addEventListener("input",(() => this.on_commit_selected()))

        outer_span.appendChild(this.commitsSelect)
        
        outer_span.insertAdjacentHTML('beforeend', "<br/><i>Note: Large time ranges can slow the version selection down.</i>")
        
        // ---
        
        this.content = document.createElement("iframe")
        this.content.className = "archive content"
        this.content.height = "100%"
        
        this.maindiv.appendChild(this.content)
        
        this.page_path = page_path
        
        this.index = index
        
        this.defaultcontent = new Blob([`
        <!doctype html><html><head>
        <style>
        body {
            min-height: 100vh;
            display: flex;
            align-items: center;
            justify-content: space-around;
        }
        
        h1,h2 {
            display: flex;
            align-items: center;
            justify-content: center;
        }
        </style>
        </head>
            <body style="background:#aaa; color:#fff;">
                <div>
                    <h1>Welcome to the archive viewer!</h1>
                    <h2>Select a date and version to start.</h2>
                </div>
            </body>
        </html>
        `], {type: "text/html"})
        this.content.src = URL.createObjectURL(this.defaultcontent)
        
        window.addEventListener('hashchange', (event) => this.on_hash_changed(event))
        
        // Updates
        this.on_hash_changed(null)
        this.update_hash() // Update visibilities
        this.load_pages() // Update version list
    }

    update_hash() {
        var old_hash = window.location.hash
        var new_hash = ""

        if (this.selecttype.value == "date") {
            new_hash = "#date=" + this.dateselector.value + "&commit=" + this.next_commit
        }
        else {
            new_hash = "#from=" + this.range_from.value + "&to=" + this.range_to.value + "&commit=" + this.next_commit
        }

        if (new_hash == old_hash) {
            return false
        }

        window.location.hash = new_hash
        return true
    }
    
    on_hash_changed(event) {
        var remaining_hash = window.location.hash.substring(1).split("&")
        
        var date_from = null
        var length = null
        var date_to = null
        var date = null

        while (remaining_hash.length > 0) {
            var current_part = remaining_hash.pop()
            
            var [key, value] = current_part.split("=")
            
            if (key == "from") {
                date_from = ""

                if (value) {
                    date_from = date_to_iso(value)
                }
            }
            else if (key == "length") {
                length = value
            }
            else if (key == "to") {
                date_to = ""

                if (value) {
                    date_to = date_to_iso(value)
                }
            }
            else if (key == "date"){
                date = ""

                if (value) {
                    date = date_to_iso(value)
                }
            }
            else if (key == "commit"){
                this.next_commit = value
            }
        }

        if (date) {
            this.dateselector.value = date
            
            this.selecttype.value = "date"

            // Convert date to range so one only needs to work with ranges
            if (this.dateselector.value) {
                var date_from_tmp = this.dateselector.value
                date_from = date_from_tmp + "T00:00"
                
                var date_to_obj = new Date(date_from_tmp)
                date_to_obj.setDate(date_to_obj.getDate() + 1)
                // Works also across months, years
                date_to = date_to_obj.toJSON().slice(0, 10) + "T00:00"
            }
        }

        if (date_from) {
            this.range_from.value = date_from
            
            this.range_to.min = date_from
            this.range_to.disabled = (date_from == "")

            if (!date) {
                this.selecttype.value = "range"
            }
        }

        if (date_to) {
            this.range_to.value = date_to
        }

        if (length) {
            this.range_to.value = date_to_iso(date_to_unix(date_from)+parseInt(length))
        }

        if (this.update_hash()) {
            return // Triggered another hash change
        }
        
        // Visibilities
        var is_date = this.selecttype.value == "date"
        this.dateselector.hidden = !is_date
        this.rangespan.hidden = is_date

        if (!is_date) {
            this.dateselector.value = ""
        }

        if (!date_from) {
            return
        }

        if (!date_to) {
            return
        }

        if (this.commitsSelect.length && date_from == this.last_from && date_to == this.last_to) {
            this.commitsSelect.value = this.next_commit
            this.on_commit_selected()
            return // List didn't change
        }

        this.last_from = date_from
        this.last_to = date_to
        
        if (this.next_commit) {
            this.load_pages(false)
            return
        }
        
        this.load_pages(true)
    }
    
    add_commits(commits, open_first) {
        var to_open = open_first
        commits.map(commit => {
            var elem = document.createElement("option")
            elem.innerHTML = commit.message
            elem.value = commit.sha
            this.commitsSelect.appendChild(elem)
            
            if (to_open) {
                this.commitsSelect.value = elem.value
                this.on_commit_selected()
                to_open = false
            }
        })
    }
    
    on_commit_selected() {
        if (!this.commitsSelect.value) {
            this.content.contentWindow.location.replace(URL.createObjectURL(this.defaultcontent))
            this.next_commit = ""
            this.update_hash()
            return
        }

        this.next_commit = this.commitsSelect.value
        this.update_hash()

        if (this.next_commit == this.current_commit) {
            return // Nothing changed
        }

        this.current_commit = this.next_commit

        var url_before = 'https://' + this.url + '/api/v4/projects/' + this.project_id + '/repository/files/' + encodeURIComponent(this.page_path + "/")
        var url_after = '/raw?ref=' + this.next_commit + '&private_token=' + this.token
        var url = url_before + encodeURIComponent(this.index) + url_after
        fetch(url)
        .then(response => response.text())
        .then(text => {
            var cleaned_text = hide_iframes(replace_urls(text, url_before, url_after))
            
            const blobContent = new Blob([cleaned_text], {type: "text/html"})
            this.content.contentWindow.location.replace(URL.createObjectURL(blobContent)) // Don't affect browser history by content change (as opposed to this.content.src = ...)
        })
    }
    
    load_pages(open_first=false) {
        var date_from = this.range_from.value
        var date_to = this.range_to.value
        
        this.load_pages_recursive(1, date_from, date_to, open_first)
    }
    
    load_pages_recursive(page, date_from, date_to, open_first) {
        if (page == 1) {
            // Clean commits list
            this.commitsSelect.innerHTML = ""
            this.commitsSelect.appendChild(document.createElement("option"))
        }
        
        if (date_from == "" || date_to == "") {
            return
        }
        
        var commits_url = 'https://' + this.url + '/api/v4/projects/' + this.project_id + '/repository/commits?ref_name=' + this.branch + '&private_token=' + this.token + "&since="+date_from+"&until="+date_to+"&per_page=100&page=" + page;
        
        var length_promise = fetch(commits_url)
        .then(response => response.json())
        .then(
            // Translate response to commits
            json => json.map(
                gitlab_commit => new ArchiveCommit(
                    gitlab_commit.message,
                    gitlab_commit.created_at,
                    gitlab_commit.id
                )
            )
        ).then((commits) => {
                // Skip if new date is selected
                if (date_from != this.range_from.value 
                    || date_to != this.range_to.value) {
                    return 0;
                }
                
                this.add_commits(commits, open_first)
                return commits.length
            }
        ).then((length) => {
            if (length > 0) {
                this.load_pages_recursive(page+1, date_from, date_to, false)
            }
            else {
                // Loading done, update commit
                this.commitsSelect.value = this.next_commit
                this.on_commit_selected()
            }
        })
    }
}