//! TipTap/ProseMirror JSON → HTML-konvertering.
//!
//! Konverterer `metadata.document` (TipTap JSON) til HTML-streng.
//! Identisk med maskinrommet/src/tiptap.rs — delt logikk.
//! Ref: oppgave 21.16 (synops-common) vil samle dette i felles crate.

use serde_json::Value;

/// Konverter et TipTap/ProseMirror-dokument (JSON) til HTML.
/// Returnerer tom streng hvis dokumentet er ugyldig.
pub fn document_to_html(doc: &Value) -> String {
    let Some(content) = doc.get("content").and_then(|c| c.as_array()) else {
        return String::new();
    };

    let mut html = String::new();
    for node in content {
        render_node(node, &mut html);
    }
    html
}

fn render_node(node: &Value, out: &mut String) {
    let node_type = node.get("type").and_then(|t| t.as_str()).unwrap_or("");

    match node_type {
        "paragraph" => {
            out.push_str("<p>");
            render_inline_content(node, out);
            out.push_str("</p>\n");
        }
        "heading" => {
            let level = node
                .get("attrs")
                .and_then(|a| a.get("level"))
                .and_then(|l| l.as_u64())
                .unwrap_or(2)
                .min(6);
            out.push_str(&format!("<h{level}>"));
            render_inline_content(node, out);
            out.push_str(&format!("</h{level}>\n"));
        }
        "blockquote" => {
            out.push_str("<blockquote>\n");
            render_children(node, out);
            out.push_str("</blockquote>\n");
        }
        "bulletList" | "bullet_list" => {
            out.push_str("<ul>\n");
            render_children(node, out);
            out.push_str("</ul>\n");
        }
        "orderedList" | "ordered_list" => {
            let start = node
                .get("attrs")
                .and_then(|a| a.get("start"))
                .and_then(|s| s.as_u64())
                .unwrap_or(1);
            if start == 1 {
                out.push_str("<ol>\n");
            } else {
                out.push_str(&format!("<ol start=\"{start}\">\n"));
            }
            render_children(node, out);
            out.push_str("</ol>\n");
        }
        "listItem" | "list_item" => {
            out.push_str("<li>");
            render_children(node, out);
            out.push_str("</li>\n");
        }
        "codeBlock" | "code_block" => {
            let lang = node
                .get("attrs")
                .and_then(|a| a.get("language"))
                .and_then(|l| l.as_str())
                .unwrap_or("");
            if lang.is_empty() {
                out.push_str("<pre><code>");
            } else {
                out.push_str(&format!("<pre><code class=\"language-{}\">", escape_html(lang)));
            }
            render_inline_content(node, out);
            out.push_str("</code></pre>\n");
        }
        "horizontalRule" | "horizontal_rule" => {
            out.push_str("<hr>\n");
        }
        "image" => {
            let attrs = node.get("attrs");
            let src = attrs
                .and_then(|a| a.get("src"))
                .and_then(|s| s.as_str())
                .unwrap_or("");
            let alt = attrs
                .and_then(|a| a.get("alt"))
                .and_then(|s| s.as_str())
                .unwrap_or("");
            let title = attrs
                .and_then(|a| a.get("title"))
                .and_then(|s| s.as_str());
            out.push_str(&format!(
                "<img src=\"{}\" alt=\"{}\"",
                escape_attr(src),
                escape_attr(alt)
            ));
            if let Some(t) = title {
                out.push_str(&format!(" title=\"{}\"", escape_attr(t)));
            }
            out.push_str(">\n");
        }
        "hardBreak" | "hard_break" => {
            out.push_str("<br>");
        }
        _ => {
            render_children(node, out);
        }
    }
}

fn render_children(node: &Value, out: &mut String) {
    if let Some(content) = node.get("content").and_then(|c| c.as_array()) {
        for child in content {
            render_node(child, out);
        }
    }
}

fn render_inline_content(node: &Value, out: &mut String) {
    let Some(content) = node.get("content").and_then(|c| c.as_array()) else {
        return;
    };

    for child in content {
        let child_type = child.get("type").and_then(|t| t.as_str()).unwrap_or("");
        match child_type {
            "text" => {
                let text = child.get("text").and_then(|t| t.as_str()).unwrap_or("");
                let marks = child.get("marks").and_then(|m| m.as_array());
                render_text_with_marks(text, marks, out);
            }
            "hardBreak" | "hard_break" => {
                out.push_str("<br>");
            }
            "image" => {
                render_node(child, out);
            }
            _ => {
                render_node(child, out);
            }
        }
    }
}

fn render_text_with_marks(text: &str, marks: Option<&Vec<Value>>, out: &mut String) {
    let Some(marks) = marks else {
        out.push_str(&escape_html(text));
        return;
    };

    let mut close_tags: Vec<&str> = Vec::new();
    for mark in marks {
        let mark_type = mark.get("type").and_then(|t| t.as_str()).unwrap_or("");
        match mark_type {
            "bold" | "strong" => {
                out.push_str("<strong>");
                close_tags.push("</strong>");
            }
            "italic" | "em" => {
                out.push_str("<em>");
                close_tags.push("</em>");
            }
            "strike" | "strikethrough" => {
                out.push_str("<s>");
                close_tags.push("</s>");
            }
            "code" => {
                out.push_str("<code>");
                close_tags.push("</code>");
            }
            "underline" => {
                out.push_str("<u>");
                close_tags.push("</u>");
            }
            "link" => {
                let href = mark
                    .get("attrs")
                    .and_then(|a| a.get("href"))
                    .and_then(|h| h.as_str())
                    .unwrap_or("#");
                let target = mark
                    .get("attrs")
                    .and_then(|a| a.get("target"))
                    .and_then(|t| t.as_str());
                out.push_str(&format!("<a href=\"{}\"", escape_attr(href)));
                if let Some(t) = target {
                    out.push_str(&format!(" target=\"{}\"", escape_attr(t)));
                }
                out.push_str(" rel=\"noopener noreferrer\">");
                close_tags.push("</a>");
            }
            _ => {}
        }
    }

    out.push_str(&escape_html(text));

    for tag in close_tags.iter().rev() {
        out.push_str(tag);
    }
}

fn escape_html(s: &str) -> String {
    s.replace('&', "&amp;")
        .replace('<', "&lt;")
        .replace('>', "&gt;")
}

fn escape_attr(s: &str) -> String {
    s.replace('&', "&amp;")
        .replace('<', "&lt;")
        .replace('>', "&gt;")
        .replace('"', "&quot;")
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde_json::json;

    #[test]
    fn simple_paragraph() {
        let doc = json!({
            "type": "doc",
            "content": [{
                "type": "paragraph",
                "content": [{ "type": "text", "text": "Hello world" }]
            }]
        });
        assert_eq!(document_to_html(&doc), "<p>Hello world</p>\n");
    }

    #[test]
    fn heading_levels() {
        let doc = json!({
            "type": "doc",
            "content": [{
                "type": "heading",
                "attrs": { "level": 2 },
                "content": [{ "type": "text", "text": "Title" }]
            }]
        });
        assert_eq!(document_to_html(&doc), "<h2>Title</h2>\n");
    }

    #[test]
    fn bold_mark() {
        let doc = json!({
            "type": "doc",
            "content": [{
                "type": "paragraph",
                "content": [{
                    "type": "text",
                    "text": "bold",
                    "marks": [{ "type": "bold" }]
                }]
            }]
        });
        assert_eq!(document_to_html(&doc), "<p><strong>bold</strong></p>\n");
    }

    #[test]
    fn html_escaping() {
        let doc = json!({
            "type": "doc",
            "content": [{
                "type": "paragraph",
                "content": [{ "type": "text", "text": "<script>alert('xss')</script>" }]
            }]
        });
        let html = document_to_html(&doc);
        assert!(!html.contains("<script>"));
        assert!(html.contains("&lt;script&gt;"));
    }

    #[test]
    fn empty_doc() {
        let doc = json!({ "type": "doc" });
        assert_eq!(document_to_html(&doc), "");
    }
}