package main

import (
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/anotherhadi/iknowyou/internal/registry"
	"github.com/anotherhadi/iknowyou/internal/tools"
)

func main() {
	out := flag.String("out", "../.github/docs", "output directory for generated docs")
	flag.Parse()

	toolsDir := filepath.Join(*out, "tools")
	if _, err := os.Stat(toolsDir); err == nil {
		if err := os.RemoveAll(toolsDir); err != nil {
			fatalf("removing tools dir: %v", err)
		}
	}

	if err := os.MkdirAll(toolsDir, 0o755); err != nil {
		fatalf("mkdir: %v", err)
	}

	runners := make([]tools.ToolRunner, len(registry.Factories))
	for i, f := range registry.Factories {
		runners[i] = f()
	}

	if err := writeIndex(*out, runners); err != nil {
		fatalf("index: %v", err)
	}
	for _, r := range runners {
		if err := writeTool(*out, r); err != nil {
			fatalf("tool %s: %v", r.Name(), err)
		}
	}

	fmt.Printf("✓ generated docs for %d tools → %s\n", len(runners), *out)
}

// writeIndex writes the tools.md index table.
func writeIndex(outDir string, runners []tools.ToolRunner) error {
	var b strings.Builder

	b.WriteString("# Tools\n\n")
	fmt.Fprintf(&b, "_%d tools registered._\n\n", len(runners))

	b.WriteString("| Tool | Input types | Description | Link |\n")
	b.WriteString("|------|-------------|-------------|------|\n")

	for _, r := range runners {
		types := make([]string, len(r.InputTypes()))
		for i, t := range r.InputTypes() {
			types[i] = fmt.Sprintf("`%s`", t)
		}
		link := fmt.Sprintf("[`%s`](tools/%s.md)", r.Name(), r.Name())
		projectLink := ""
		if r.Link() != "" {
			projectLink = fmt.Sprintf("[Link](%s)", r.Link())
		}
		fmt.Fprintf(&b, "| %s | %s | %s | %s |\n",
			link,
			strings.Join(types, ", "),
			r.Description(),
			projectLink,
		)
	}

	return writeFile(filepath.Join(outDir, "tools.md"), b.String())
}

// writeTool writes the per-tool detail page.
func writeTool(outDir string, r tools.ToolRunner) error {
	var b strings.Builder

	fmt.Fprintf(&b, "# `%s`\n\n", r.Name())
	fmt.Fprintf(&b, "%s\n\n", r.Description())

	if r.Link() != "" {
		fmt.Fprintf(&b, "**Source / documentation:** [%s](%s)\n\n", r.Link(), r.Link())
	}

	// Input types
	b.WriteString("## Input types\n\n")
	for _, t := range r.InputTypes() {
		fmt.Fprintf(&b, "- `%s`\n", t)
	}
	b.WriteString("\n")

	// External binary dependencies
	if lister, ok := r.(tools.DependencyLister); ok {
		if deps := lister.Dependencies(); len(deps) > 0 {
			b.WriteString("## External dependencies\n\n")
			b.WriteString("The following binaries must be installed and available in `$PATH`:\n\n")
			for _, dep := range deps {
				fmt.Fprintf(&b, "- `%s`\n", dep)
			}
			b.WriteString("\n")
		}
	}

	// Configuration
	if d, ok := r.(tools.ConfigDescriber); ok {
		fields := d.ConfigFields()
		if len(fields) > 0 {
			b.WriteString("## Configuration\n\n")
			b.WriteString("Configure globally via the Tools page or override per profile.\n\n")
			b.WriteString("| Field | Type | Required | Default | Description |\n")
			b.WriteString("|-------|------|:--------:|---------|-------------|\n")
			for _, f := range fields {
				req := "-"
				if f.Required {
					req = "**yes**"
				}
				def := "-"
				if f.Default != nil && fmt.Sprintf("%v", f.Default) != "" {
					def = fmt.Sprintf("`%v`", f.Default)
				}
				desc := f.Description
				if desc == "" {
					desc = "-"
				}
				fmt.Fprintf(&b, "| `%s` | `%s` | %s | %s | %s |\n",
					f.Name, f.Type, req, def, desc,
				)
			}
			b.WriteString("\n")
		} else {
			b.WriteString("## Configuration\n\nThis tool has no configuration fields.\n\n")
		}
	} else if _, ok := r.(tools.Configurable); ok {
		b.WriteString("## Configuration\n\nThis tool is configurable but does not expose field metadata.\n\n")
	} else {
		b.WriteString("## Configuration\n\nThis tool requires no configuration.\n\n")
	}

	b.WriteString("---\n\n")
	b.WriteString("[← Back to tools index](../tools.md)\n")

	return writeFile(filepath.Join(outDir, "tools", r.Name()+".md"), b.String())
}

func writeFile(path, content string) error {
	return os.WriteFile(path, []byte(content), 0o644)
}

func fatalf(format string, args ...any) {
	fmt.Fprintf(os.Stderr, "gendocs: "+format+"\n", args...)
	os.Exit(1)
}