add metadata model

[vincentsarago]

ref #30

This PR adds a SearchMetadata model defining the mosaic metadata that could be provided by the user when registering a search request.

Metadata

{
    // OPTIONAL. Default: "mosaic" (No other value accepted for now). Describe the `type` of metadata. 
    "type": "mosaic",

    // OPTIONAL. Default: null.
    // The maximum extent of available map tiles. The bounds are represented in WGS:84
    // latitude and longitude values, in the order left, bottom, right, top.
    // Values may be integers or floating point numbers.
    "bounds": [ -180, -85.05112877980659, 180, 85.0511287798066 ],

    // OPTIONAL. Default: null.
    // An integer specifying the minimum zoom level.
    "minzoom": 0,

    // OPTIONAL. Default: null.
    // An integer specifying the maximum zoom level. MUST be >= minzoom.
    "maxzoom": 11,

    // OPTIONAL. Default: null. The name can contain any legal character.
    "name": "compositing",

    // OPTIONAL. Default: null. An array of available assets.
    "assets": ["image", "cog"],

    // OPTIONAL. Default: null. A set of `defaults` configuration.
    "defaults": {
        "true_color": {
            "assets": ["B4", "B3", "B2"],
            "color_formula": "Gamma RGB 3.5 Saturation 1.7 Sigmoidal RGB 15 0.35",
        },
        "ndvi": {
            "expression": "(B4-B3)/(B4+B3)",
            "rescale": "-1,1",
            "colormap_name": "viridis"
        }
    }
}

[vincentsarago]

FYI: @drnextgis

[drnextgis]

Awesome! As soon as it is merged, I will update the example in the documentation.

[vincentsarago]

🙏 , for now I'm still waiting for some feedback on the metadata model

[vincentsarago]

d3eecdc#diff-0f0c40de44a0841ed5180f16d66212d1cece2a7d4400789007c2f73bf8432622L39 I updated the docs 🙏

[vincentsarago]

Metadata will always be set when registering a search with the RegisterMosaic. default metadata should be {"type": "mosaic"}

[drnextgis]

Looks good to me. Just one question: what is the purpose of having SearchType.search?

[vincentsarago]

@drnextgis

what is the purpose of having SearchType.search?

I guess my goal is to quickly differentiate search requests registered through titiler-pgstac and other search entries. This way when we do #40 we can only filter on type=="mosaic". the type SearchType.search will be set by default for search entries that doesn't have the type SearchType.mosaic (not used for now, but maybe later)

[vincentsarago]

FYI: I'm going to merge this to Master, but anyone interested can still make comments over #30