//! Markdown renderer for ArchDoc
//!
//! This module handles generating Markdown documentation from the project model
//! using templates.

use crate::model::ProjectModel;
use handlebars::Handlebars;

fn sanitize_for_link(filename: &str) -> String {
    filename
        .chars()
        .map(|c| match c {
            '/' | '\\' | ':' | '*' | '?' | '"' | '<' | '>' | '|' => '_',
            c => c,
        })
        .collect()
}

pub struct Renderer {
    templates: Handlebars<'static>,
}

impl Renderer {
    pub fn new() -> Self {
        let mut handlebars = Handlebars::new();
        
        // Register templates
        handlebars.register_template_string("architecture_md", Self::architecture_md_template())
            .expect("Failed to register architecture_md template");
        
        // Register module documentation template
        handlebars.register_template_string("module_md", Self::module_md_template())
            .expect("Failed to register module_md template");
        
        Self {
            templates: handlebars,
        }
    }
    
    fn architecture_md_template() -> &'static str {
        r#"# ARCHITECTURE — {{{project_name}}}

<!-- MANUAL:BEGIN -->
## Project summary
**Name:** {{{project_name}}}
**Description:** {{{project_description}}}

## Key decisions (manual)
{{#each key_decisions}}
- {{{this}}}
{{/each}}

## Non-goals (manual)
{{#each non_goals}}
- {{{this}}}
{{/each}}
<!-- MANUAL:END -->

---

## Document metadata
- **Created:** {{{created_date}}}
- **Updated:** {{{updated_date}}}
- **Generated by:** archdoc (cli) v0.1

---

## Integrations
<!-- ARCHDOC:BEGIN section=integrations -->
> Generated. Do not edit inside this block.

### Database Integrations
{{#each db_integrations}}
- {{{this}}}
{{/each}}

### HTTP/API Integrations
{{#each http_integrations}}
- {{{this}}}
{{/each}}

### Queue Integrations
{{#each queue_integrations}}
- {{{this}}}
{{/each}}
<!-- ARCHDOC:END section=integrations -->

---

## Rails / Tooling
<!-- ARCHDOC:BEGIN section=rails -->
> Generated. Do not edit inside this block.
{{{rails_summary}}}
<!-- ARCHDOC:END section=rails -->

---

## Repository layout (top-level)
<!-- ARCHDOC:BEGIN section=layout -->
> Generated. Do not edit inside this block.
| Path | Purpose | Link |
|------|---------|------|
{{#each layout_items}}
| {{{path}}} | {{{purpose}}} | [details]({{{link}}}) |
{{/each}}
<!-- ARCHDOC:END section=layout -->

---

## Modules index
<!-- ARCHDOC:BEGIN section=modules_index -->
> Generated. Do not edit inside this block.
| Module | Symbols | Inbound | Outbound | Link |
|--------|---------|---------|----------|------|
{{#each modules}}
| {{{name}}} | {{{symbol_count}}} | {{{inbound_count}}} | {{{outbound_count}}} | [details]({{{link}}}) |
{{/each}}
<!-- ARCHDOC:END section=modules_index -->

---

## Critical dependency points
<!-- ARCHDOC:BEGIN section=critical_points -->
> Generated. Do not edit inside this block.
### High Fan-in (Most Called)
| Symbol | Fan-in | Critical |
|--------|--------|----------|
{{#each high_fan_in}}
| {{{symbol}}} | {{{count}}} | {{{critical}}} |
{{/each}}

### High Fan-out (Calls Many)
| Symbol | Fan-out | Critical |
|--------|---------|----------|
{{#each high_fan_out}}
| {{{symbol}}} | {{{count}}} | {{{critical}}} |
{{/each}}

### Module Cycles
{{#each cycles}}
- {{{cycle_path}}}
{{/each}}
<!-- ARCHDOC:END section=critical_points -->

---

<!-- MANUAL:BEGIN -->
## Change notes (manual)
{{#each change_notes}}
- {{{this}}}
{{/each}}
<!-- MANUAL:END -->
"#
    }
    
    fn module_md_template() -> &'static str {
        r#"# Module: {{{module_name}}}

{{{module_summary}}}

## Symbols

{{#each symbols}}
### {{{name}}}

{{{signature}}}

{{{docstring}}}

**Type:** {{{kind}}}

**Metrics:**
- Fan-in: {{{fan_in}}}
- Fan-out: {{{fan_out}}}
{{#if is_critical}}
- Critical: Yes
{{/if}}

{{/each}}

## Dependencies

### Imports
{{#each imports}}
- {{{this}}}
{{/each}}

### Outbound Modules
{{#each outbound_modules}}
- {{{this}}}
{{/each}}

### Inbound Modules
{{#each inbound_modules}}
- {{{this}}}
{{/each}}

## Integrations

{{#if has_db_integrations}}
### Database Integrations
{{#each db_symbols}}
- {{{this}}}
{{/each}}
{{/if}}

{{#if has_http_integrations}}
### HTTP/API Integrations
{{#each http_symbols}}
- {{{this}}}
{{/each}}
{{/if}}

{{#if has_queue_integrations}}
### Queue Integrations
{{#each queue_symbols}}
- {{{this}}}
{{/each}}
{{/if}}

## Usage Examples

{{#each usage_examples}}
```python
{{{this}}}
```

{{/each}}
"#
    }
    
    pub fn render_architecture_md(&self, model: &ProjectModel) -> Result<String, anyhow::Error> {
        // Collect integration information
        let mut db_integrations = Vec::new();
        let mut http_integrations = Vec::new();
        let mut queue_integrations = Vec::new();
        
        for (symbol_id, symbol) in &model.symbols {
            if symbol.integrations_flags.db {
                db_integrations.push(format!("{} in {}", symbol_id, symbol.file_id));
            }
            if symbol.integrations_flags.http {
                http_integrations.push(format!("{} in {}", symbol_id, symbol.file_id));
            }
            if symbol.integrations_flags.queue {
                queue_integrations.push(format!("{} in {}", symbol_id, symbol.file_id));
            }
        }
        
        // Prepare data for template
        let data = serde_json::json!({
            "project_name": "New Project",
            "project_description": "<FILL_MANUALLY: what this project does in 3–7 lines>",
            "created_date": "2026-01-25",
            "updated_date": "2026-01-25",
            "key_decisions": ["<FILL_MANUALLY>"],
            "non_goals": ["<FILL_MANUALLY>"],
            "change_notes": ["<FILL_MANUALLY>"],
            "db_integrations": db_integrations,
            "http_integrations": http_integrations,
            "queue_integrations": queue_integrations,
            // TODO: Fill with more actual data from model
        });
        
        self.templates.render("architecture_md", &data)
            .map_err(|e| anyhow::anyhow!("Failed to render architecture.md: {}", e))
    }
    
    pub fn render_module_md(&self, model: &ProjectModel, module_id: &str) -> Result<String, anyhow::Error> {
        // Find the module in the project model
        let module = model.modules.get(module_id)
            .ok_or_else(|| anyhow::anyhow!("Module {} not found", module_id))?;
        
        // Collect symbols for this module
        let mut symbols = Vec::new();
        for symbol_id in &module.symbols {
            if let Some(symbol) = model.symbols.get(symbol_id) {
                symbols.push(serde_json::json!({
                    "name": symbol.qualname,
                    "signature": symbol.signature,
                    "docstring": symbol.docstring_first_line.as_deref().unwrap_or("No documentation available"),
                    "kind": format!("{:?}", symbol.kind),
                    "fan_in": symbol.metrics.fan_in,
                    "fan_out": symbol.metrics.fan_out,
                    "is_critical": symbol.metrics.is_critical,
                }));
            }
        }
        
        // Collect integration information for this module
        let mut db_symbols = Vec::new();
        let mut http_symbols = Vec::new();
        let mut queue_symbols = Vec::new();
        
        for symbol_id in &module.symbols {
            if let Some(symbol) = model.symbols.get(symbol_id) {
                if symbol.integrations_flags.db {
                    db_symbols.push(symbol.qualname.clone());
                }
                if symbol.integrations_flags.http {
                    http_symbols.push(symbol.qualname.clone());
                }
                if symbol.integrations_flags.queue {
                    queue_symbols.push(symbol.qualname.clone());
                }
            }
        }
        
        // Prepare usage examples (for now, just placeholders)
        let usage_examples = vec![
            "// Example usage of module functions\n// TODO: Add real usage examples based on module analysis".to_string()
        ];
        
        // Prepare data for template
        let data = serde_json::json!({
            "module_name": module_id,
            "module_summary": module.doc_summary.as_deref().unwrap_or("No summary available"),
            "symbols": symbols,
            "imports": model.files.get(&module.files[0]).map(|f| f.imports.clone()).unwrap_or_default(),
            "outbound_modules": module.outbound_modules,
            "inbound_modules": module.inbound_modules,
            "has_db_integrations": !db_symbols.is_empty(),
            "has_http_integrations": !http_symbols.is_empty(),
            "has_queue_integrations": !queue_symbols.is_empty(),
            "db_symbols": db_symbols,
            "http_symbols": http_symbols,
            "queue_symbols": queue_symbols,
            "usage_examples": usage_examples,
        });
        
        self.templates.render("module_md", &data)
            .map_err(|e| anyhow::anyhow!("Failed to render module.md: {}", e))
    }
    
    pub fn render_integrations_section(&self, model: &ProjectModel) -> Result<String, anyhow::Error> {
        // Collect integration information
        let mut db_integrations = Vec::new();
        let mut http_integrations = Vec::new();
        let mut queue_integrations = Vec::new();
        
        for (symbol_id, symbol) in &model.symbols {
            if symbol.integrations_flags.db {
                db_integrations.push(format!("{} in {}", symbol_id, symbol.file_id));
            }
            if symbol.integrations_flags.http {
                http_integrations.push(format!("{} in {}", symbol_id, symbol.file_id));
            }
            if symbol.integrations_flags.queue {
                queue_integrations.push(format!("{} in {}", symbol_id, symbol.file_id));
            }
        }
        
        // Prepare data for integrations section
        let data = serde_json::json!({
            "db_integrations": db_integrations,
            "http_integrations": http_integrations,
            "queue_integrations": queue_integrations,
        });
        
        // Create a smaller template just for the integrations section
        let integrations_template = r#"

### Database Integrations
{{#each db_integrations}}
- {{{this}}}
{{/each}}

### HTTP/API Integrations
{{#each http_integrations}}
- {{{this}}}
{{/each}}

### Queue Integrations
{{#each queue_integrations}}
- {{{this}}}
{{/each}}
"#;
        
        let mut handlebars = Handlebars::new();
        handlebars.register_template_string("integrations", integrations_template)
            .map_err(|e| anyhow::anyhow!("Failed to register integrations template: {}", e))?;
        
        handlebars.render("integrations", &data)
            .map_err(|e| anyhow::anyhow!("Failed to render integrations section: {}", e))
    }
    
    pub fn render_rails_section(&self, _model: &ProjectModel) -> Result<String, anyhow::Error> {
        // For now, return a simple placeholder
        Ok("\n\nNo tooling information available.\n".to_string())
    }
    
    pub fn render_layout_section(&self, model: &ProjectModel) -> Result<String, anyhow::Error> {
        // Collect layout information from files
        let mut layout_items = Vec::new();
        
        for (_file_id, file_doc) in &model.files {
            layout_items.push(serde_json::json!({
                "path": file_doc.path,
                "purpose": "Source file",
                "link": format!("docs/architecture/files/{}.md", sanitize_for_link(&file_doc.path))
            }));
        }
        
        // Prepare data for layout section
        let data = serde_json::json!({
            "layout_items": layout_items,
        });
        
        // Create a smaller template just for the layout section
        let layout_template = r#"

| Path | Purpose | Link |
|------|---------|------|
{{#each layout_items}}
| {{{path}}} | {{{purpose}}} | [details]({{{link}}}) |
{{/each}}
"#;
        
        let mut handlebars = Handlebars::new();
        handlebars.register_template_string("layout", layout_template)
            .map_err(|e| anyhow::anyhow!("Failed to register layout template: {}", e))?;
        
        handlebars.render("layout", &data)
            .map_err(|e| anyhow::anyhow!("Failed to render layout section: {}", e))
    }
    
    pub fn render_modules_index_section(&self, model: &ProjectModel) -> Result<String, anyhow::Error> {
        // Collect module information
        let mut modules = Vec::new();
        
        for (module_id, module) in &model.modules {
            modules.push(serde_json::json!({
                "name": module_id,
                "symbol_count": module.symbols.len(),
                "inbound_count": module.inbound_modules.len(),
                "outbound_count": module.outbound_modules.len(),
                "link": format!("docs/architecture/modules/{}.md", sanitize_for_link(module_id))
            }));
        }
        
        // Prepare data for modules index section
        let data = serde_json::json!({
            "modules": modules,
        });
        
        // Create a smaller template just for the modules index section
        let modules_template = r#"

| Module | Symbols | Inbound | Outbound | Link |
|--------|---------|---------|----------|------|
{{#each modules}}
| {{{name}}} | {{{symbol_count}}} | {{{inbound_count}}} | {{{outbound_count}}} | [details]({{{link}}}) |
{{/each}}
"#;
        
        let mut handlebars = Handlebars::new();
        handlebars.register_template_string("modules_index", modules_template)
            .map_err(|e| anyhow::anyhow!("Failed to register modules_index template: {}", e))?;
        
        handlebars.render("modules_index", &data)
            .map_err(|e| anyhow::anyhow!("Failed to render modules index section: {}", e))
    }
    
    pub fn render_critical_points_section(&self, model: &ProjectModel) -> Result<String, anyhow::Error> {
        // Collect critical points information
        let mut high_fan_in = Vec::new();
        let mut high_fan_out = Vec::new();
        
        for (symbol_id, symbol) in &model.symbols {
            if symbol.metrics.fan_in > 5 {  // Threshold for high fan-in
                high_fan_in.push(serde_json::json!({
                    "symbol": symbol_id,
                    "count": symbol.metrics.fan_in,
                    "critical": symbol.metrics.is_critical,
                }));
            }
            if symbol.metrics.fan_out > 5 {  // Threshold for high fan-out
                high_fan_out.push(serde_json::json!({
                    "symbol": symbol_id,
                    "count": symbol.metrics.fan_out,
                    "critical": symbol.metrics.is_critical,
                }));
            }
        }
        
        // Prepare data for critical points section
        let data = serde_json::json!({
            "high_fan_in": high_fan_in,
            "high_fan_out": high_fan_out,
            "cycles": Vec::<String>::new(), // TODO: Implement cycle detection
        });
        
        // Create a smaller template just for the critical points section
        let critical_points_template = r#"

### High Fan-in (Most Called)
| Symbol | Fan-in | Critical |
|--------|--------|----------|
{{#each high_fan_in}}
| {{{symbol}}} | {{{count}}} | {{{critical}}} |
{{/each}}

### High Fan-out (Calls Many)
| Symbol | Fan-out | Critical |
|--------|---------|----------|
{{#each high_fan_out}}
| {{{symbol}}} | {{{count}}} | {{{critical}}} |
{{/each}}

### Module Cycles
{{#each cycles}}
- {{{this}}}
{{/each}}
"#;
        
        let mut handlebars = Handlebars::new();
        handlebars.register_template_string("critical_points", critical_points_template)
            .map_err(|e| anyhow::anyhow!("Failed to register critical_points template: {}", e))?;
        
        handlebars.render("critical_points", &data)
            .map_err(|e| anyhow::anyhow!("Failed to render critical points section: {}", e))
    }
    
    pub fn render_layout_md(&self, model: &ProjectModel) -> Result<String, anyhow::Error> {
        // Collect layout information from files
        let mut layout_items = Vec::new();
        
        for (_file_id, file_doc) in &model.files {
            layout_items.push(serde_json::json!({
                "path": file_doc.path,
                "purpose": "Source file",
                "link": format!("files/{}.md", sanitize_for_link(&file_doc.path))
            }));
        }
        
        // Prepare data for layout template
        let data = serde_json::json!({
            "layout_items": layout_items,
        });
        
        // Create template for layout.md
        let layout_template = r#"# Repository layout

<!-- MANUAL:BEGIN -->
## Manual overrides
- `src/app/` — <FILL_MANUALLY>
<!-- MANUAL:END -->

---

## Detected structure
<!-- ARCHDOC:BEGIN section=layout_detected -->
> Generated. Do not edit inside this block.
| Path | Purpose | Link |
|------|---------|------|
{{#each layout_items}}
| {{{path}}} | {{{purpose}}} | [details]({{{link}}}) |
{{/each}}
<!-- ARCHDOC:END section=layout_detected -->
"#;
        
        let mut handlebars = Handlebars::new();
        handlebars.register_template_string("layout_md", layout_template)
            .map_err(|e| anyhow::anyhow!("Failed to register layout_md template: {}", e))?;
        
        handlebars.render("layout_md", &data)
            .map_err(|e| anyhow::anyhow!("Failed to render layout.md: {}", e))
    }
    
    pub fn render_symbol_details(&self, model: &ProjectModel, symbol_id: &str) -> Result<String, anyhow::Error> {
        // Find the symbol in the project model
        let symbol = model.symbols.get(symbol_id)
            .ok_or_else(|| anyhow::anyhow!("Symbol {} not found", symbol_id))?;
        
        // Prepare data for symbol template
        let data = serde_json::json!({
            "symbol_id": symbol_id,
            "qualname": symbol.qualname,
            "kind": format!("{:?}", symbol.kind),
            "signature": symbol.signature,
            "docstring": symbol.docstring_first_line.as_deref().unwrap_or("No documentation available"),
            "purpose": symbol.purpose,
            "integrations": {
                "http": symbol.integrations_flags.http,
                "db": symbol.integrations_flags.db,
                "queue": symbol.integrations_flags.queue,
            },
            "metrics": {
                "fan_in": symbol.metrics.fan_in,
                "fan_out": symbol.metrics.fan_out,
                "is_critical": symbol.metrics.is_critical,
                "cycle_participant": symbol.metrics.cycle_participant,
            },
            "outbound_calls": symbol.outbound_calls,
            "inbound_calls": symbol.inbound_calls,
        });
        
        // Create template for symbol details
        let symbol_template = r#"<a id="{{symbol_id}}"></a>

### `{{qualname}}`
- **Kind:** {{kind}}
- **Signature:** `{{{signature}}}`
- **Docstring:** `{{{docstring}}}`

#### What it does
<!-- ARCHDOC:BEGIN section=purpose -->
{{{purpose}}}
<!-- ARCHDOC:END section=purpose -->

#### Relations
<!-- ARCHDOC:BEGIN section=relations -->
**Outbound calls (best-effort):**
{{#each outbound_calls}}
- {{{this}}}
{{/each}}

**Inbound (used by) (best-effort):**
{{#each inbound_calls}}
- {{{this}}}
{{/each}}
<!-- ARCHDOC:END section=relations -->

#### Integrations (heuristic)
<!-- ARCHDOC:BEGIN section=integrations -->
- HTTP: {{#if integrations.http}}yes{{else}}no{{/if}}
- DB: {{#if integrations.db}}yes{{else}}no{{/if}}
- Queue/Tasks: {{#if integrations.queue}}yes{{else}}no{{/if}}
<!-- ARCHDOC:END section=integrations -->

#### Risk / impact
<!-- ARCHDOC:BEGIN section=impact -->
- fan-in: {{{metrics.fan_in}}}
- fan-out: {{{metrics.fan_out}}}
- cycle participant: {{#if metrics.cycle_participant}}yes{{else}}no{{/if}}
- critical: {{#if metrics.is_critical}}yes{{else}}no{{/if}}
<!-- ARCHDOC:END section=impact -->

<!-- MANUAL:BEGIN -->
#### Manual notes
<FILL_MANUALLY>
<!-- MANUAL:END -->
"#;
        
        let mut handlebars = Handlebars::new();
        handlebars.register_template_string("symbol_details", symbol_template)
            .map_err(|e| anyhow::anyhow!("Failed to register symbol_details template: {}", e))?;
        
        handlebars.render("symbol_details", &data)
            .map_err(|e| anyhow::anyhow!("Failed to render symbol details: {}", e))
    }
}